فرسایش

The catchment area of the Talar River in Mazandaran Province is subject to annual flooding events that facilitate the transport of substantial quantities of silt. To investigate sediment transport dynamics within this watershed, samples were collected at five designated sections along an 11-kilometer segment of the Talar River. The sampling intervals were delineated as follows: 24.7–22.4 km, 18.2–20.5 km, 17.5–18 km, 16.75–17.5 km, and 11.5–16.75 km, measured from the urban area of Malakala-Najjarkala to Arab Roshan, with all distances calculated from the shoreline. This study aimed to analyze sedimentation and erosion patterns over a five-year period (2016–2021) employing the HEC-RAS model. Sediment transport and volume were assessed based on long-term data obtained from the Kiakla hydrometric station, with a specific focus on flood conditions associated with return periods of 2, 10, 25, 50, and 100 years. The findings indicate that the cumulative sediment input at the beginning of the monitored section is 0.9 million tonnes lower than the total sediment at the end. The river exhibits a pronounced tendency towards erosion. In the first section (22.4–24.7 km), the mean sediment height is 11 cm, accompanied by significant sedimentation totaling 6 million tonnes. The second section reflects an approximate deposition of 1 million tonnes. The third section demonstrates a relatively stable sediment pattern. In the fourth section, the conditions for erosion—both in terms of depth and volume—are deemed unsuitable for sediment harvesting. The fifth section (11.5–16.75 km) records erosion amounting to approximately 8.3 million tonnes, with height variations ranging from 10 to 20 cm. Under these circumstances, sediment removal is impractical; However, the implementation of flood management strategies and river engineering interventions is strongly recommended.

Erosion is a factor that severely threatens soil productivity and is one of the greatest obstacles to achieving sustainable development in agriculture and using natural resources. Land use changes can change the physical properties of the land surface and expose the soil to erosion by affecting the type of land use and its spatial patterns. Meshkinshahr County (located in Ardabil Province), due to its environmental characteristics, has a high potential for erosion risk. However, in recent years, due to the growing population and unprincipled land-use changes, the potential for this risk to occur at the county level has increased. Therefore, given the importance of the subject, in the present study, the study of land use changes and their role in the occurrence of erosion risk has been studied in the period between 2002 and 2024.

In this study, to investigate land use changes, first, Landsat satellite images from (OLI-TM) sensors for the years (2002 and 2024) were obtained from the US Geological Survey. Then, to prepare the images, geometric and atmospheric corrections were made to the images using the Flash method and Envi5.3 software. In the next stage, using the object-oriented classification method and the nearest neighbor algorithm by Ecognition software, land use maps were extracted in the two study periods. In the next stage, by identifying the effective factors involved in the erosion of the region (including; land use, slope, lithology, soil, distance from road, distance from river, and precipitation) and preparing information layers for each criterion in GIS, the valuation and standardization of the layers were carried out using the fuzzy membership function and weighting of the criteria, using the critic method. Finally; final analysis and modeling were performed using the WLC multi-criteria analysis method.

The results show that in the two time periods studied, the largest area of the area is covered by poor pastures and rainfed agriculture, and the lowest level of land use is related to snow-covered lands and water areas. According to the results of the study, during the period studied, the area of land used for irrigated agriculture, rainfed agriculture, residential areas, and water areas has increased. So in 2024, compared to 2002, rainfed agriculture increased by 203.78 square kilometers, irrigated agriculture by 63.06 square kilometers, residential areas by 54.48 square kilometers, and areas with water cover by 1.19 square kilometers. In contrast, the area of garden and forest land uses, good pastures, poor pastures, and snow-covered lands has decreased in 2024 compared to 2002. The results show that during the study period, the area of poor and good pastures has increased by: 180.95 and 118.59 square kilometers have decreased. The area of garden and forest lands in the county has decreased by 22.47 square kilometers in 2024, and snow cover has also decreased by 0.5 square kilometers.According to the results of weighting the criteria, in 2002, the criteria of slope, land use, lithology, and soil have the highest weight coefficients, respectively, and in 2024, the criteria of land use, slope, lithology, and soil have the highest weight coefficients.According to the erosion zoning map, in 2002, the area of the very high-risk and high-risk categories was 216.308 and 779.068 square kilometers, and the amount of these risk categories has increased to 600.348 and 820.228 square kilometers in 2024, respectively.

The high extent of the very high-risk and high-risk classes in both periods of study indicates the very high erosion potential of this county, given the environmental conditions prevailing in the area. Looking at the results of the analysis of land use changes and their compliance with the erosion risk potential maps, in addition to environmental conditions (such as the presence of loose soils, sensitive and erodible formations, high slope, rainfall, and abundance of the waterway network), the reduction in the area of pastures, orchards, and forest cover, and the increase in the area of agricultural lands (irrigated and dry) and residential areas can be stated as the most important reasons for the increase in soil erosion potential in Meshkinshahr County. Finally, according to the research results, to manage the land use of the county systematically, measures such as strengthening and restoring the vegetation cover of pastures, reducing the pressure of pasture exploitation by providing alternative jobs, converting low-yielding rainfed lands to forage crops, raising public awareness about the consequences of converting pasture lands to rainfed lands, familiarizing farmers with protective measures on sloping lands and how to cultivate them, and training them on methods of combating soil erosion are suggested.

Soil erosion represents a critical environmental challenge, with land use changes being the primary factors that exacerbate its potential. Meshkinshahr County has long been susceptible to erosion due to its environmental characteristics, while population growth and unprincipled land use changes have further heightened this risk at the county level in recent years. This study aims to evaluate the impact of land use changes on soil erosion in Meshkinshahr County. To achieve the research objectives, land use maps for the years 2002 and 2024 were generated using an object-oriented approach. Subsequently, additional layers of factors influencing erosion were prepared using Geographic Information Systems (GIS). Erosion zoning was then conducted by standardizing these layers with a fuzzy function, weighting the criteria using the CRITIC method, and modeling with the VIKOR multi-criteria decision-making algorithm. The analysis of land use changes revealed that, in both time periods, poor pastures and dryland agriculture occupied the largest areas within the county. According to the erosion zoning map, in 2002, the areas classified as very high-risk and high-risk constituted 10.88 and 26.55%, respectively. By 2024, these figures increased to 14.14 and 27.33%. Overall, the study indicated that the reduction of pastures, gardens, and forest cover combined with the increase in agricultural (both irrigated and dryland) and residential land uses were the primary drivers behind the heightened potential for soil erosion in the county.

Soil erosion is a natural geomorphic process. An increasing number of studies show that changes in the rate of erosion and sediment yield in watershed are often strongly correlated with seismicity. Peak ground acceleration is equal to the maximum acceleration of the ground that occurred during the shaking of the earthquake in a place. Therefore, the purpose of this study is to investigate the relationship between soil erosion and seismic activities and erosion control factors, how high erosion zones are related to the Peak ground acceleration and other factors, and to compare the efficiency of two fuzzy logic and entropy models in erosion zoning.

Talar drainage basin is located on both sides of Qaimshahr-Tehran axis. In terms of geographic coordinates, it is located between ˚52 '35 "22 to˚53 '23 "34 east longitude and ˚35 '44 "23 to ˚36 '19 "1 north latitude. For this purpose, important indices such as erosivity, erodibility, slope-length, cover management have been calculated in the RUSLE equation. Then, the zoning map of the peak ground acceleration has been used as the erosion control factor using the seismic hazard analysis method obtained in the study (Ashtari et al., 2023).

Fuzzy logic and entropy:

For the purpose of zoning, all the layers produced in the previous step were placed as base layers in fuzzy logic and entropy models. Linear function was used to quantify all layers in fuzzy logic. In order to combine the layers, the fuzzy gamma operator was used. In the entropy model, based on the map of erosion levels from specialized studies of the Talar drainage basin, the number of sample sites in each of the erosion zones is as follows: The areas of surface erosion are (16), lateral stream erosion (10), groove erosion (9), gully erosion (8), rock and rock mass erosion (6) and badland erosion (1). The steps of the entropy method are as follows: forming the decision matrix, Ej function and determining the value of entropy, calculating the degree of deviation of criteria dj, determining the weight of each criterion Wij, regional erosion risk model Hi.

Rainfall erosivity factor: This factor expresses the kinetic energy of rain when the drops hit the soil particles, and in other words, it is the intensity of precipitation and erosion resulting from the impact of rain drops on the ground during rainfall. The highest and lowest amount of this factor is respectively in the northern side of the sub-basin 3 with (369-457-8) and in the southern side of the sub-basin 1 with (13.9-102).Erodibility factor: It is in accordance with the average sensitivity factor of formations to erosion of sub-basin 1 (6.09), sub-basin 2 (6.39), sub-basin 3 (7.6). Due to the extent and variety of geological formations, there is a high potential for erosion in all 3sub-basins.length - slope: which is also known as the topography factor, is a function of the height in the basin. The lowest amount of this factor is in the areas of valleys and river streams (>6) and the highest amount corresponds to slopes and heights (>23).cover management: Vegetation factor represents the amount of vegetation waste in different uses. The lower the amount of c, the more vegetation in the area. The highest coefficient c (0.5-0.6) is in sub-basin 1, which indicates the decrease of vegetationand the potential for erosion, and the lowest c (0.2-0.3) in sub-basin 3, which indicates the richness of land uses from forest vegetation.Peak ground acceleration factor: The highest amount of ground acceleration is near the active faults in the region. Due to the structure of the faults, which have an east-west trend, in all 3 sub-basins there are areas of maximum ground acceleration during each event. The highest areas of ground acceleration levels (0.5-0.6) are sub-basin 1 and the lowest are sub-basin 3, which is due to the structure of active faults such as Firuzukuh fault, IRQ112 and IRQ357.

The highest area is in the very low class (839 km2 and 39.9 %) and the lowest area is in the low class (162.9 km2 and 7.7 %). The largest expansion of the mentioned areas is located in sub-basin 1. The distribution of high and very high-risk areas especially in sub-basin 2 and the low coverage of these areas in sub-basin 1 do not match with the relative contribution of high sediment production in sub-basin 1 based on studies.Erosion zonation map by entropy methodThe results of the entropy model showed that the erodibility factor was 20.62%, the peak ground acceleration factor was 20.20%, the cover management was 20%, the erosivity factor was 19.60%, and the slope-length factor was 19.58% in the occurrence of erosion in the region. The area of very high risk with 13.5% of the area of the basin includes erosional facies containing surface, groove, gully and lateral stream. In general, it can be said that the highest erosion risk zones are not related to the highest weighting of the layers, but the placement of a set of factors influencing the occurrence of erosion, which shows the highest amount of erosion.

The peak ground acceleration has a direct impact on the control of sediment yield and erosion processes. The placement of a small part of the IRQ112 fault has caused the extent of ground acceleration levels (0.5-0.6) to be less in sub-basin 3 and more in sub-basin 1 due to the placement of 3 faults, Firuzukuh, IRQ112 and IRQ357. The placement of erodible formations in the ranges of peak ground acceleration has caused the process of sediment production and erosion to accelerate. The coordination of the erosion occurrence zones with the ground acceleration levels is due to the regionality of the entropy model in contrast to the fuzzy model.

The analysis of some geological features and structures can be used to determine Quaternary developments. Analyzing the types of landslides, their density, and scale is the key to identify the evolution of landforms. Based on this, the current research was carried out with the aim of spatial analysis of landslides that occurred in different lithologies of Mo’alem-Kelayeh basin, a part of eastern Alamut basin, between the longitudes 50°26'00″ to 50°31'20″ and the latitude 36°22'00″ to 36°30'00″, based on topographical, geological conditions, vegetation, the condition of waterways, and the proximity of different rocks in the area. According to the results, the Karaj, Rute, Shamshek and Neogene and destructive sediments are the most erodible formations in the studied area, which are the most important factors involved in the occurrence of mass movements on a micro and macro scale under the Mo’alem-Kelayeh basin. The nonresistant lithology is more extensive in the geographical levels downstream of the rivers. In such areas, in addition to the loosening of the lithology in wide sections, the material and energy flowing in the river also increases, if due to the lower slope of the slopes, the effect of the river on movements of the slopes becomes more limited. In the terrestrial levels close to the ridge line, matter and energy are less and lithology is more resistant; But due to greater slope of the slopes and the involvement of physical weathering in the porosity of rocks, the effect of river on the occurrence of surface slope movements increases.

The topography is, directly and indirectly, affects the geomorphic processes and hydrological behavior of the slope (Prancevic and Kirchner, 2019), therefore, quantitative correlation of topography features is possible due to deposition and runoff production and predicting the spatial distribution of soil and surface deposits (McKenzie and Ryan, 1999). different shapes and sides of slopes in the drainage basin affect the time of runoff movement on the slopes and drainage networks and the basin response, such as time, equilibrium, retardation time, concentration-time, and hydrograph peak time. These temporal features constitute an important part of the hydrological modeling of the watershed. Considering that most of rainfall-runoff models relate to runoff traverse times at the slopes surface, it is easy to study the topography effect on runoff features such as river discharge estimators, flood forecasting, peak flow, runoff volume, and water resource management (Merheb et al., 2016; Mlynski et al., 2019). In terms of morphodynamic conditions, the topography is directly related to erosion and sedimentation processes. Topographic wetness index theory (TWI) is designed as an important and all-purpose feature in the rainfall-runoff model to measure the effect and topography controlling on hydrological processes (Calogero et al., 2015; Jeziorska and Niedzielski, 2018; Xue et al., 2018). This model simulates the interaction of groundwater and surface water with topography to determine which regions are prone to saturation of the earth and thus have a high potential for surface accumulation water (Ballerine, 2017) and can be expressed quantitatively as a physical indicator the effect of the topography of watersheds slopes on the mechanism of substructure flow (groundwater), runoff production, the spatial distribution of soil moisture and the ability of soil moisture deficiency to saturation state at each point in the range and level of the basin. (Beven and Kirkby 1979; O'Loughlin 1986; Barling et al. 1994; Qiu et al., 2017).

The Maroon River drainage basin, with an area of 7228 square kilometers and an area of 802 kilometers, covers the central part of the Jarahi-Zohreh basin. The Jarahi-Zohreh basin is itself a large part of the Persian Gulf-Oman Sea basin, which its drainage network pours into the northwest part of the Persian Gulf (Fig. 1). In this study, the based data obtained have formed 30 m SRTM DEM data, 1:50000 topographic maps, geological maps of 1:100000, aerial photos, Landsat satellite imagery, Google Earth, and field visits and ArcGIS10.3, QGIS, and SAGA software. To estimate topographic indices, first, it is processed the DEM data file and the stream network of the study basin in the SAGA software environment and then topographic basin indices based on DEM data were calculated and analyzed by the existing functions of this software. In the continuation, slopes of the Maroon basin were classified into nine different types based on two indices of plan shape (divergence, convergence, parallel) and profile (curvature) slopes profile (concave, convex, and flat) (Fig. 2) and the obtained amount of TWI index was analyzed in them. a: The hydrological model (TOPMODEL) is a semi-distributed model where the topography changes of the region and participating levels play a major role in the runoff, assuming that hydraulic gradient can be estimated using the land topography gradient (Ballerine, 2017). The topographic information used in this model is introduced as a topographic moisture indicator and can express the topography effect on runoff production and slope movements quantitatively. These values are calculated using the digital elevation model (DEM) of the studied area and by measuring the flow direction, current accumulation, gradient, and different geometrical characteristics obtained from Arc Hydro software. The final result is a Raster layer which shows pathways (regions) with drainage ditches where water is likely to accumulate there (Ballerine, 2017).

The results of basin type stud show that the first-class waterways flow mostly in divergent basins with flat curvature. The second, third, and fourth classes of the basin flow in the concave and parallel basin, and the fifth and sixth classes flow in convex and convergent basins (Table 1). In divergent slopes of the basin, the topographic moisture index has been reduced and in convex and convergent basins, the topographic moisture index increases. Furthermore, the TWI index has a high inverse correlation with the degree gradient and average height of the river (-0.97). This index decreases with the increasing gradient and height of waterways (Table 2). In the trimming basins, the increasing general gradient has led to an acceleration of water flow, thus the time required for penetrating water flow and rainfalls is decreased and the concentration-time is decreased too, and correspondingly amount of erosion and water wasting is increased.

The results of the study show that the topographic features of the basin-like the slope plan and longitudinal profile of the slope play a decisive role in hydrological processes and runoff time features and slope response time. These features not only directly affect geomorphological and hydrological conditions like annual runoff, flood volume, soil erosion intensity, and sediment production, but also indirectly effects the climate, ecological situation, and vegetation, as well as effects on the water situation in the basin. The results of the basin slope type study are such that the divergent slopes are the lowest amount in the topographic moisture index. Surface water and subsurface water is not concentrated, they spread, and pass slopes water rapidly. the results showed that there is a significant relationship between hydrological processes with the topography and geomorphology indices and can be used as a variable to simulate the moisture state of the Maroon basin area, which is an example of an indirect and low-cost approach to study the hydrological and geomorphological features of the region. the consistency of this index to local soil conditions is a certain advantage over the existing methods and in detailed application programs it needs to perform more activity and perform adaptive studies. Therefore, knowledge of these indices and features in terms of impact on the variability of soil hydraulic features and surface Sediment is necessary to achieve sustainable development and reorganization of the region.

Soil erosion is one of the important issues in the watersheds of Iran and can be considered as one of the most important barriers to achieving sustainable agriculture and natural resources. This study was conducted to compare the MPSYAK, EPM and BLM models using kappa statistical coefficient to assess soil erosion and sediment production in the Seymareh-e-Charnar catchment area. For this purpose, the position of 90 points of erosion points was determined in a field survey by a GPS device and these points were adapted to the final erosion maps.The evaluation of the results obtained from the models used by the Kappa statistical coefficient shows that the MPSYAK model with Kappa statistical coefficient is 0.91 compared to the APM and BLM models with a kappa statistical coefficient of 0.76 and 0.71 of greater accuracy In assessing the risk of erosion in the Seymareh Chenar catchment area. Also, the results of the overlaying of the final erosion mapwith erosion points showed that in the AP model, 81% of the points in the medium-risk zone, the BBL model had 37% of these points in the medium-risk zone and in the M-PSYAK model 90% of the specified points In the middle danger area.
Therefore, it can be said that the studied area is in the middle erosion class and the M-PSIAC model shows more accurate results for erosion evaluation in this basin. Based on the zoning done using the M-PSYAK model, 7.93, 14.45, 77.62% of the area of the area is located in very low, medium and low risk classes. Also, based on the APM model, 27.44%, 32.16%, 40.40% of the area of the area were in low, moderate, high risk classes, respectively. The results of this model estimated the coefficient of erosion intensity of 0.58 and the total sediment produced during one year was 1921183.6 cubic meters.

Today, soil erosion is considered one of the most important problems in the world, and due to the long period of soil formation in Iran, the importance of this problem is more prominent in this country. This annual process causes the destruction of land, the reduction of soil fertility and the filling of reservoirs of dams. The best place for erosion control is catchment areas. It is necessary to pay attention to watersheds in the process of erosion, especially the basins whose rivers play an important role in providing drinking water for residential areas, agriculture and river treatment projects. In this research, using hydrophysical models (CSY), the sedimentation potential of the sub-basins of the Ruain River catchment area in the southern slopes of Aladagh Mountains in northeastern Iran was calculated. The results of this research showed that factors such as size, topography, erodibility, precipitation and vegetation cover in the sub-basins of this river basin have the greatest effect on the sedimentation potential of the sub-basins of this river, and the erosion and sedimentation potential is the same in all the sub-basins of this river. is not. Based on this, the sedimentation potential for Ruin sub-basin was 390.05 tons equivalent to 47.84%, for Mahmoudi sub-basin 182.04 tons equivalent to 22.32%, for Kalat sub-basin 143.91 tons equivalent to 17.65% and for Shiravieh sub-basin 99.27 equivalent to 12.17%. Therefore, the Ruin and Mahmoudi sub-basins are more sensitive to erosion processes than the other two sub-basins and should be properly managed by implementing soil protection plans and proper management of the erosion process.Erosion is the movement of soil from one place to another and in any possible way, the natural process of this process is necessary for nature, but a large amount of it will lead to unfortunate consequences such as the filling of lakes and dams, the reduction of soil fertility, the increase of the sediment load of rivers and the destruction of ecosystems. had Erosion occurs under the influence of various factors, and knowledge of these factors will have a significant effect on reducing erosion and sediment load of rivers. Today, the increase of sediment measuring stations in river catchment areas has made it easy to measure their sediment load, and most of the world's rivers are equipped with these stations, with all the possible improvements in this field, some catchment areas still lack this device. In addition, these stations cannot predict the amount of erosion in the future, and it is not possible to install measuring devices for all basins and their sub-basins, so estimating the amount of erosion and sedimentation of the watershed using the model Experimental studies can be considered as a suitable program to protect the soil and prevent the harmful effects of erosion and help to obtain reliable data in the stations.Due to the high rate of erosion and the slowness of soil formation, the study of this process gained more speed. With the presentation of the cycle of erosion by Morris Davis in 1884, the process of erosion attracted the attention of more researchers (Shahdad, 2009). With the passage of time and the increase of agricultural activities, erosion became more intense and the need for scientific studies in this field increased and became academic and many experimental methods such as USLE, MPSIAC, WEPP, EPM, SWAT, MUSLE, geomorphology, Hydrophysics, Musgrave and... were presented and researchers such as Gavrilovich (1988), Weiss Kamir and Smith (1978), Musgrave (1947), Gab Hart and Johnson (1982) (1982), Zonta in Italy and... in this field conducted studies (Maqami Moghim et al. 1402). In Iran, due to the long time of formation, the high rate of soil erosion and the lack of equipment and hydrometric stations, experimental methods of estimating sedimentation and erosion have attracted the attention of researchers, and researchers such as Mahmoud Abadi (1384), Naderi (1389), Khosravi 1390), Qadzavi (1391), Ahmadi (1396) and Haghi Abhi (1398). Conducted studies in this field. One of the new methods of experimental estimation of erosion among the methods proposed in Iran that has attracted the attention of Iranian researchers is The hydrophysical method is CSY, which has been used by researchers in Iran due to its ease. In a study conducted in the Nozhian watershed in Lorestan province, a jury concluded that the hydrophysical model is more accurate compared to the EPM and MPSIAC models. (Davari et al., 2014). In another study in the Kesilian basin of Mazandaran, compared to the geomorphological method, the results of the hydrophysical method had a greater distance with the statistics recorded at the hydrometric station of this basin (Mohsani et al., 2015). Damghan River used this method to estimate erosion potentials and considered it a suitable method to estimate sediment in a relative manner in this basin (Maqami Moghim et al., 1402). With this method, it is possible to identify the erodible points of the basin more easily, as a result, planning for high-risk points is done with more precision (Ahmadi, 2016). Ruin River is one of the watersheds of the southern slopes of Aladagh highlands in the northeast of Iran, which has received less attention from researchers. . The abundant accumulation of sediment in the alluvial cone of this river indicates severe erosion in its catchment area (Figure 1). Despite severe erosion, its sedimentation and erosion potential has not been studied. The only information related to the sediment measurement of this river is its hydrometric station, which is located in the southwest of Iraqi village which records the sedimentation of this river in general. For this reason, the information about the erosion potential in the sub-basins of this river is still unknown. This can cause many problems for the people living in this area, especially the industrial complex in the south of this basin as the largest industrial complex in northeastern Iran. For this reason, it is necessary to calculate its sedimentation potential for the principled exploitation of natural resources and reducing the harm of erosion.

This research performed for assessment of erosion condition of the Tajyar catchment located in NW of Iran with regard to the importance of soil erosion, especially in mountainous catchments. In this way, it was tried to estimate erosion and sediment yield rates using EPM and MPSIAC models based on ability of geographic information system (GIS). Data used involved maps, satellite photos, statistic of weather and water gage stations. Results indicated that it was considerable differences between the models with point of estimated erosion and sediment yield, so that estimated total sediment yield is equal to 99342/76 ton per year in MPSIAC model and 16089/37 ton per year in EPM model, it showed that studied catchment is placed in medium erosion class using MPSIAC model and in low erosion class using EPM model. Finally, it concluded that MPSIAC model has better efficiency than EPM model because involving more factors, joining influence of factors in hand and more accuracy of pointing tables and related equations in other hand. However calibration of MPSIAC model in order reduction of errors and more accurate prediction can give more good and trusty results

Soil erosion is inevitable phenomenon that seriously threatens soil and water resources; and is a function of several factors, which are based on certain conditions of each region; one or more agents may be effective in its intensifications. So the study of soil erosion, assessment of variables, and affective parameters is essential.In the method study of a library-based research studies, the field, and the use of quantitative models to estimate erosion and sediment, ARC GIS software is used. Considering that in soil erosion, several parameters systematically are effective and recognizing them as affecting factors on the rate of erosion and sediment is very important. So among the various methods of estimating erosion and sediment, EPM method is used as a selected techniques and Environmental Parameters in its model due to conforming weather condition in Iran.The result suggests that the study basin of severity of erosion is in class four –the low erosion-. The rate of total erosion and sediment of basin is respectively estimated by 239997.68 and 206396.3 cubic meters per year.

Soil erosion is one of the most important geomorphological processes on the earth's surface, which has accelerated due to human intervention. This process causes many damages such as loss of fertile soils, destruction of infrastructure and filling of dams. In the assessment of soil erosion, several factors should be used in a combined and integrated manner. In this regard, in basins without data or with limited data, a set of geomorphological indicators can be used in combination with other indicators and the erosion potential can be evaluated. In the current research, the erosion potential of Firouzabadchay catchment area located in Ardabil province has been evaluated. In this regard, 13 indicators, mainly geomorphological, were used. In order to combine and overlapped the layers, fuzzy logic was used in the context of the geographic information system (GIS). The results show the high potential of soil erosion in the surface of the Firozabad catchment area. Several factors are effective in the erodibility of the basin's soils, which in this context can be the wide outcrop of Quaternary alluvial formations, gypsum marls, lahar and volcanic ash, weak vegetation, predominance of steep slopes, high drainage density, existence of numerous streams, high values of roughness number and long slopes. In zones of the study basin where several factors affecting erosion have favorable conditions, the rate of erosion has intensified. In this regard, we can mention the central sub-basins of the study basin, which are among the critical areas of the basin due to the presence of alluvial and marl formations, weak vegetation, high slope, high drainage density and several other factors.

Among the various methods of controlling desertification, the method of using plants that are compatible with this environment is considered the most suitable method. Plants are considered as one of the elements of this measure, but in the revitalization plans of arid and semi-arid areas, it is necessary to check the mutual influence of the cultivated species on the soil of the cultivated areas. The effect that plants have on the soil below them causes physical and chemical changes in the soil. By knowing the ecological needs of these species and comparing them with the existing conditions of new environments; In order to increase the productivity and meet the goals of restoration projects on the one hand and to know the effects of these species on the cultivation environment on the other hand, it is possible to firstly prevent the occurrence of financial losses due to the failure of cultivation due to the incompatibility of the species and secondly to prevent the creation of new stressful conditions in the areas under The effect of the species and finally, by using the obtained results, it is possible to recommend the plant species in the conditions of the environment similar to the study area.

The studied area is a part of Yazd-Ardakan Plain, the total area of ​​the project is 117,600 hectares (267 hectares of the field were selected for sampling). The average annual rainfall is about 64 millimeters, the average temperature is 21 degrees Celsius. The prevailing wind direction is mostly northwest and blows with an average speed of 4.5 meters per second. An area without any type of plant species with the same soil and geomorphological conditions was considered as a control. Sampling was done by random-systematic method under the canopy and in the control area at the soil surface depth (0-30 cm). Out of the 30 samples, 25 of which were collected in the field of tag work and 5 samples were collected as controls. It was harvested weighing about 2 kg. Factors (texture, organic matter, electrical conductivity, acidity, magnesium, calcium, sodium, and potassium) were measured in the laboratory. The results of the experiments were entered into SPSS software, and the normality of the data was first tested. After determining the results of normality, the independent parametric t test was used to analyze the normal data, and the non-parametric Mann-Whitney test was used for the non-normal data.

After entering the SPSS software, the data obtained from the samples were tested for normality with the Kolmogorov Smirnov test and the Shapiro-Wilk test. The purpose of performing the data normality test is that it helps us in using parametric or non-parametric tests for the next steps, the parameters of sand percentage, clay percentage, sodium, calcium and SAR are not normal. So, non-parametric test was used to analyze these parameters. The rest of the investigated parameters followed the normal distribution and parametric test was used for analysis.

The results of the data normality test showed that the parameters of sand percentage, clay percentage, sodium, calcium and SAR parameters do not follow the normal distribution and the parameters of electrical conductivity (EC), acidity (PH), carbon, potassium, silt, magnesium and ESP parameters are normal. using the results of the statistical test, points were given in the following way: in the investigated parameters that had a significant difference between the field and the control, if that parameter caused soil modification, a positive score was given, and if it had a negative effect on the soil A negative score was given. The calculated evaluation score for the cultivated area was +3, which shows that the soil had a better condition than the control area in terms of potassium, organic carbon, and magnesium. and have no witnesses. The parameters of potassium, organic carbon and magnesium have a significant difference at the probability level of 5%, which is distinguished by an arrow in the figure. The results of frequency analysis and independent t-tests and Mann-Whitney for the investigated parameters are explained as follows. Regarding the electrical conductivity, the results indicated that there is no significant difference in the field of tag work with the control. In terms of acidity (PH), the results showed that there is no significant difference between the treated area and the control area, and the soils of both environments are alkaline. However, it is not consistent in most of the researches such as Al-Gadi (2008), Rahimizadeh et al. (2009) who stated the increase in pH under the cultivation area as the result of their research. The results show a significant increase in the potassium element in the soil of the cultivated field compared to the control field. So that the amount of this element has increased from 366 to about 1299 mg, that is, it has increased about 4 times. This difference is statistically significant with a probability of 99%. In general, as mentioned above, the soil was not significantly different from the control field in terms of physical properties. In terms of chemical properties of the soil, only three parameters of organic carbon, potassium and magnesium have increased significantly in the soil, which shows that the soil has been strengthened in terms of these elements. Of course, the presence of these elements in the soil under the plant is due to their absorption from the depth of the soil by the plant roots and storage in the plant leaves. which accumulates at the foot of the plant after falling. Of course, it should not be overlooked that the salinity of the soil at the foot of the plants has increased compared to the control. And in terms of salinity, the soil condition has not improved.

The purpose of this research is to evaluate the amount of soil loss in the land uses of the Nirchai watershed using the RUSLE model in Ardabil province. In order to carry out this research, first, the satellite image of the studied area related to the year 1400 and the month of June was received from the American Geological Research Center, and after atmospheric and radiometric corrections, a land use map was prepared using the supervised classification method using the support vector machine method. Then the RUSLE model was used to estimate the erosion rate. SPSS 21, Excel, ArcGIS 5.4, Archydro and ENVI 5.3 software were used to analyze and produce maps in this research. RUSLE model parameter layer includes rain erosion layer, soil layer, topography layer, vegetation layer and soil protection factor as well as various statistics related to rain gauge stations, hydrometry, topographic maps 1:50000, geology 1:100000 as well as DEM (20 meters area) and GIS geographic information system and remote sensing have been used. The results of this study showed that the average amount of annual soil erosion for the whole basin ranges from 0.5 to 14.25 tons per hectare per year. Also, the investigation of the regression relationships between the factors of RUSLE model and the amount of annual soil erosion showed that the topography factor (LS) with the highest value of the coefficient of determination R^2=0.93 is the most important in estimating the annual soil erosion using the RUSLE model.

Soil erosion has been increasing in Iran in the last decade due to the lack of optimal use of pasture and forest lands. This factor destroys the ecological conditions suitable for the life of organisms while wasting the soil and producing sediment. Preservation and development of vegetation in pastures, such as medicinal plants, plays a significant role in preventing soil erosion. Salvia macrosiphon Boiss is a perennial species and has an essential oil plant of the Lamiaceae family, which is traditionally used in the treatment of respiratory diseases, depression and urinary tracts. Considering that in recent years, due to the economic and export value of this species, its natural habitats have been overexploited, and also due to climate changes and extensive droughts of the past few years, as well as harvesting in this way, the process of soil erosion in its natural habitats has been accelerated. Therefore, the present study was conducted with the aim of investigating 19 ecological attributes of the main habitats of S. macrosiphon in Fars and Hormozgan provinces.

In the current study, the natural habitats of this species were determined by using Flora Iranica and with the assistance of Hormozgan Agricultural Research, Education and Extension Organization experts. Characteristics of five habitats in Fars province (including Kazeroon, Farashband, Dehram, Evaz and Jahrom) and three habitats in Hormozgan province (including ZahedMahmoud, Bekhan and Sirmand) were studied. The climatic features of each natural habitat such as latitude and longitude, altitude, mean annual temperature, minimum and maximum temperature, and mean annual precipitation were recorded. From each habitat, three soil samples were taken from a depth of 0-30 cm. The percentages of clay, silt, sand, pH, electrical conductivity (EC), organic carbon, absorbable phosphorus, absorbable potassium, total nitrogen, calcium carbonate equivalent (CCE), absorbable iron, absorbable zinc, absorbable manganese and absorbable copper were measured. To analyze the studied environmental factors and the measured soil parameters, the multivariate analysis method including Pearson correlation coefficient of traits, decomposition into principal components and cluster analysis was used by SPSS ver. 26 software.

The results revealed that S. macrosiphon was distributed at an altitude of 400 to 1550 meters above sea level in Kazeroon, Farashband, Dehram, Evaz, Jahrom, ZahedMahmoud, Bekhan and Sirmand natural habitats and on the slope between 0 to 20%. The maximum and minimum annual rainfall were recorded as 156.2 and 387.7 mm, respectively. The average annual temperature was recorded at 24.5 °C and also, the minimum and maximum temperatures were -3.8 and +49.5, respectively. This species grows in the loam, sandy loam and silt loam soil textures with a pH of 7.7-8.4, an EC of 0.47-6.87 dS/m. Furthermore, it was found that S. macrosiphon was spread in non-saline and saline soils (electrical conductivity 0.47 to 6.87 dS/m). The soil in which the species was grown in the studied areas was poor in terms of available potassium content (46 to 302 ppm). The highest concentration of absorbable Fe (6.7 mg/kg) in Farashband habitat, absorbable Zn (3.8 mg/kg) in Kazeroon habitat, absorbable Mn (0.28 mg/kg) in Kazeroon habitat and absorbable Cu (0.2 mg/kg) was observed in Zahedmahmoud habitat. On the other hand, the lowest concentration of absorbable Fe (1.5 mg/kg), absorbable Zn (0.6 mg/kg) and absorbable Mn (3.3 mg/kg) was observed in Dehram habitat. Also, the lowest amount of absorbable Cu (0.3 mg/kg) was obtained in the two habitats of Dehram and Evaz. Using cluster analysis, habitats were divided into four clusters according to which habitats with common characteristics were placed in the same group.

The findings of this study showed that S. macrosiphon is resistant to hot and dry conditions. The two habitats of Dehram and Zahedmahmoud are prone to flooding due to the high percentage of silt in the soil texture. A high percentage of silt increases soil runoff during rainfall because the silt texture of the soil is one of the factors that prevents water from penetrating the soil. If the percentage of silt in the soil texture is high, the soil can absorb less water, and as a result, more water flows during rainfall, which can lead to soil erosion. The lack of absorbable phosphorus and potassium, as well as the lack of nitrogen and organic carbon, are the most obvious attributes of the soil of the S. macrosiphon habitats, which may cause limitations in its growth. The parent material of the soils of the studied areas originates from calcite limestone. In areas where the soil is calcareous, the temperature and pH are high. Based on the estimated Pearson correlation coefficient between the traits, it was determined that the higher organic carbon soil will have the higher amount of nitrogen. The presence of organic matter and the amount of nutrients have a direct relationship. This means that wherever the amount of organic matter is higher, the amount of nutrients is also higher. On the other hand, an increase in temperature leads to a decrease in soil organic matter. The results of analysis into the main components led to the extraction of five factors, which, according to the effectiveness of the variables, the selection based on the first component will lead to habitats with heavier soil texture and higher potassium concentration, which can provide a possibility of pasture development by this species in soils with a higher clay content and wide range of temperature fluctuations. In general, this research demonstrates considering the importance of S. macrosiphon in terms of being an under-expected pasture and medicinal species, as well as taking into account limitations such as low rainfall, and irregular spatial and temporal changes. Due to (limited) rainfall, high evaporation and transpiration and unprincipled exploitation, the condition of the habitats is extremely fragile and will lead to the instability of these ecosystems. By planning and conducting optimal management of pasture and medicinal resources through the obtained information, it is possible to domesticate and cultivate this plant by following the microclimatic conditions of this plant and providing natural conditions for its growth and protecting its valuable genetic resources. After all, these studies help us to be able to use optimal methods to improve and preserve the soil and prevent its erosion through plant preservation.

Erosion is primarily caused by precipitation and runoff, while erodibility results from the type of the formations at the catchment scale, which is subject of this study. The objective of this study was to investigate the relationship between geologic units and erosion intensity. Initially, two models of MPSIAC and Fargas were used to study erosion intensity. The Fargas model was presented based on the theoretical principles of two erosion and the erodibility factors, while MPSIAC model was based on 9 factors. BLM method was used to separate the intensities of a type of erosion according to the S.S.F table. RUSLE model was used to estimate soil erosion in the studied sub-basins. To determine the risk of erosion using the value coefficient, Fargas model was used. In the MPSIAC model, coefficients were considered for each of the nine factors. Based on the results of MPSIAC model, 79% of the basin surface had high erosion intensity and 21% had very high erosion intensity, while according to Fargas model, 0.3% had moderate erosion intensity, 10% had high erosion intensity, and 4.7% and 85% were characterized with severe erosion and very severe erosion, respectively. Moreover, in both models, 18% corresponded to very high erosion intensity (very severe), while 7.2% had high erosion intensity. In Fargas model, E1t1, E1t2, E2ig3, Q2f, Qt1, and Qt2 had very strong erosion intensity, whereas, in MPSIAC model, E1t1, Qt1, and Qt2 had high erosion intensity on their surfaces. One reason for this phenomenon could be the erodibility of the formations. Most of E1t2 and Q2t are highly eroded, which contributes to a large amount of drainage in addition to the erodibility of the formations.

During the recent decades, the loss of water and soil resources in watersheds due to their inappropriate exploitation has become increasingly intense, this issue has reduced the production and useful life of reservoirs and increased the amount of sediment production. Today, with the advancement of technology, examining the impact of projects by measuring the effective parameters and studying how to achieve the goals are part of the basic principles of project evaluation. In this study, according to the implemented mechanical and biological operations, the role of watershed operations in controlling erosion and sedimentation in the Saqezchi-chay watershed of Ardabil province was investigated and compared using the MPSIAC method before and after the operation. In this model, 9 effective factors in erosion have been considered, each of which has a score depending on its intensity and weakness, and finally, taking these scores into account, the sedimentation rate of the area is considered. The results of the research show a relative decrease in erosion and sedimentation in the area of watershed operations and, on the other hand, an increase in erosion and sedimentation in other areas without watershed operations, which indicates the positive effect of watershed operations in increasing vegetation and soil protection. Also, the implemented watershed management measures, in addition to increasing the concentration time in the watershed and groundwater feeding, have played an important role in preventing the reduction of the storage volume of the Saqezachi dam. The results indicate the effectiveness of watershed projects in reducing sedimentation in the study area; In such a way that the amount of erosion in the watershed has changed significantly.

Today, soil erosion is one of the important problems in catchments, lakes behind the dam, various agricultural areas and natural resources, which also causes land degradation, reduced soil fertility and filling the reservoir of dams. Due to climatic conditions, the erosion process in Iran requires more attention because in this country, soil formation occurs in the long run and its destruction in the short term. The best place to control soil erosion is catchments. It is necessary to pay attention to catchments in the erosion process, especially catchments whose rivers flow into lakes behind dams or play an important role in providing drinking water to a city or region. In this study, using the hydrophysical model (CSY), the sedimentation potential of Damghan River watershed in the southern slopes of Alborz was calculated. The results of this study showed that the Namakeh sub-basin has the highest and the Dibaj sub-basin has the lowest sedimentation potential. The Kalateh Rudbar basin is also in moderate conditions. Therefore, the Namakeh basin is more vulnerable to erosion and should be properly managed by implementing soil protection plans and proper management of the erosion process in this basin.

Determining the type of relationship between different components of soil erosion can provide more complete information about the performance of these components in different watersheds and land uses. In this study, in order to determine the type of relationship between different components of soil erosion in different land uses of Gachsaran Formation deposits, a part of Kuhe Gach watershed with an area of 1202 hectares was selected. In this study, using univariate regression, the type of relationships between sediment - runoff, sediment - infiltration, sediment - runoff and erosion threshold, runoff - infiltration, runoff - runoff and erosion threshold, infiltration - runoff and erosion threshold were determined and also, the relationship between them was also examined. Sampling of erosion different components at 6 points with 3 replicates and at different rainfall intensities of 0.75, 1 and 1.25 mm/min in three land uses of the range, residential area and agricultural lands using a rain simulator was performed. SPSS and EXCEL software were used for statistical analysis. The results showed that in general in the intensity of 0.75 mm/min in all three land uses, range, agricultural and residential and in the relationship between all the different components of soil erosion in seven cases, there is a positive relationship and in eleven cases, there is a negative relationship. And at an intensity of 1 mm/min in all three rang, agricultural and residential land uses and in the relationship between all the different components of soil erosion in seven cases, there is a positive relationship and in eleven cases, there is a negative relationship. And at an intensity of 1.25 mm/min in all three uses of the range, agricultural and residential land uses and in the relationship between all the different components of soil erosion in eight cases, there is a positive relationship and in ten cases, a negative relationship.

 The goal of this study was to investigate the relationship between vegetation and soil erosion and changes to the hydro-geochemical properties of water. Soil erosion is closely related to the type of vegetation and land use, and can change water quality in a region. For this, the present study collected and analyzed 15 water samples from the permanent waterways of Pirbadush and Gashun of the Qolyan River in the Qalikuh region of Lorestan, Iran. According to studies, from higher parts of the highlands of the region down towards downstream areas, water quality is reduced with the reduction of vegetation and increase of soil erosion and progressive Quaternary sediments, and with the entry of more cations and anions from sediments to water, and increased electrical conductivity, the total dissolved solids and turbidity. Thus, greater levels of vegetation in the highlands of this region increase soil permeability and reduce soil erosion. In this region, the reduced vegetation depends on the type of bedrock, and in some areas excessive grazing, in addition to altitude changes, thus increasing pollutants such as nitrates. Increased nitrates in the regional water depend on anthropogenic (livestock grazing) and geo-genic (expanded oil shales and the erosion of Quaternary deposits) factors. As a consequence, the regional water quality is more influenced by environmental and geo-genic factors, with anthropogenic factors less contributing to it.

Soil erosion has been considered as the primary cause of soil degradation because soil erosion leads to the loss of topsoil and soil organic matter, which are essential for the growing of plants. Quantification of soil loss is a significant issue for soil and water conservation practitioners and policy makers. At the watershed level, the two most important hydrological phenomena that can occur from rainfall procedures are surface runoff and soil erosion.There are many models to study the soil erosion. One of the most widely used model for estimating this phenomenon is the Revised Universal Soil Loss Equation (RUSLE). Six factors are included in the RUSLE model: Rainfall erosivity, soil erodibility, slope length and steepness, vegetation cover and management and supporting practices. In this study, multi-sources data are used to generate the necessary parameters of the RUSLE model. Since Surface runoff and soil erosion are the two significant hydrologic reactions, the Soil Conservation Service Curve Number (SCS-CN) model is used to estimate runoff. This study has shown that a strong relationship between the surface runoff estimation and the maximum erosion potential in the study area. The advantage offered by this model is its simplicity and the diversity of the parameters used reflecting the function of runoff under the hydrological system.