Environmental Erosion Research Journal

---

Extended abstract
1- Introduction
Soil erosion is one of the most important environmental issues that causes various ecological, social and economic problems. Today, the use of various models for estimating and predicting hydrological data of watersheds is increasing. Soil erosion risk assessment is a special form of land resources evaluation, and its purpose is to divide the land into small areas based on the type of erosion and its amount, which is essential in the soil conservation planning. Developing comprehensive soil erosion models applicable in different environmental conditions is highly important. The Intensity of Erosion and Outflow (IntErO) model is a new graphical model that has a user-friendly software and could present a comprehensive view from watershed erosional components. Awareness of important coefficients such as watershed development, river basin tortuousness, erosion energy of the basin's relief, the region's permeability, vegetation cover, and deposit retention coefficients that provided by IntErO model has a key role to adapt proper watershed management and conservative measures, particularly the best management practices (BMPs) that are currently considered by policymakers and executive managers.
 
2- Methodology
Due to the positive reports on the proper efficiency of the IntErO model in some parts of the areas such as Bosnia & Herzegovina, Bulgaria, Croatia, Czech Republic, Italy, Brazil, and recently in North Khorasan and Kurdistan provinces, the present study was conducted with the aim of obtaining comprehensive information on the erosional characteristics of the KoozehTopraghi Watershed located in the southern part of Ardabil Province. The studied watershed with an area of 801.40 km² was divided into 36 sub-watersheds according to topographical and hydrological properties. Totally, the IntErO program package for estimating soil erosion and sediment yield components uses 26 input data including geometric, topographic, maximum outflow, hydrological and soil erosion intensity properties. All primary maps for total watershed and its 36 sub-watersheds were processed and provided in the ArcGIS 10.6 environment. Then, according to the required standards of the model, the data bank was provided in the Excel 2016 environment and accordingly uploaded to the IntErO software. Finally, after running the IntErO model, 22 components related to the soil erosion process of KoozehTopraghi Watershed were obtained.
3- Results
According to the results of the IntErO model, the spatial variability was confirmed in relation to the most of erosional components through 36 sub-watersheds which indicate the diversity of ecological and biophysical conditions at the whole watershed. In general, the maximum and minimum ​​of soil erosion coefficient (Z) were estimated in the sub-watersheds 6 and 10, respectively. According to the obtained results, most of the study sub-watersheds have experienced severe erosion. It was also found that the mean of the production of erosion material in the river basin (Wgod) was equal to 222854.65 m³ y^-1, respectively whereby it’s minimum and maximum were obtained in the sub-watersheds 6 and 33, respectively. The reason for the high amount of specific sediment yield in some sub-watersheds can be attributed to their severe exploitation for human needs and consequently severe erosion. The results also showed that the mean value and standard deviation of the coefficient of the deposit retention (Ru) for the whole watershed was 0.26 ± 0.09. The values ​​of real soil loss (Ggod) and specific real soil loss (Ggod/km²) were evaluated as 172704.90 m³ y^-1 and 215.50 m³ km² y^-1. The results showed that there was a lot of permeability in the upland sub-watersheds. In these sub-watersheds, due to the existence of rangelands and higher vegetation cover, more water penetrates.
4- Discussion & Conclusions
In general, the results showed that the erosion values ​​at the lowlands of the study watershed are much higher than at the highlands. The present results are consistent with the other researches that reported the high level of ecological sensitivity in the lowlands of ​​the KoozehTopraghi Watershed. The results of the present study can be used as a useful managerial tool in the field of sustainable agricultural production and optimal use of natural resources. Finally, it is recommended to compare the applicability of the IntErO model in different environmental conditions, considering its comprehensiveness in analyzing the erosional status. The results of this study, in addition to its capability for modeling different watershed ecological, hydrological and managerial processes, their analysis is useful to prioritize the critical regions as well as sustainable and effective implantation of restoration and conservative practices in the KoozehTopraghi Watershed.

---

1- Introduction
Today, the increasing population and, consequently, the demand for agricultural products have caused the natural cover of land, especially forests and pastures to be destroyed by humans at an alarming rate to become agricultural land; even in many areas due to lack of water and nutrients, vegetation growth is limited. Declining vegetation worldwide due to human activities such as overgrazing and deforestation reduces permeability and consequently increases runoff and can reduce soil particle adhesion and predisposes fertile soil particles to erosion. Soil erosion in managed ecosystems such as crops, pastures, or forests, as well as in natural ecosystems leads to extensive damage. It also reduces the infiltration capacity due to runoff and reduces soil organic matter and thus valuable soil nutrients. At the same time, it significantly reduces the diversity of plant and animal species. To this end, controlling soil erosion is one of the most important goals in water conservation and management programs. Vegetation can be a very important tool to control water erosion and regenerate the ecosystem. Vegetation reduces the shear stress by increasing the roughness and decreasing the water flow velocity, and the hydraulic resistance created by the vegetation causes the absorption and deposition of suspended sediments. Vegetation and its associated factors on a long-term scale also play an important role in modifying the hydrological properties and soil erodibility and sediment load. The role of vegetation in reducing runoff and soil erosion in different studies has been proven. However, the effects of different vegetation compositions have not been studied extensively in runoff and soil erosion control. Accordingly, the present study was planned to investigate the effect of different compositions of graminea and bushes with different coverage percentages on runoff and sediment components.  
2- Methodology
The study area is part of the natural rangelands located in the surroundings of the University of Mohaghegh Ardabili, Ardabil, NW of Iran. A total of nine treatments from different vegetation compositions including low-height graminea predominance (T1), the composition of dense bushes with graminea (T2), bushes with low-height and medium-distribution (T3), sparse bushes mostly with low and medium height (T4), the composition of sparse bushes with graminea (T5), dense bushes in upper parts (T6), low-height bushes with very low distribution (T7), dense bushes with almost uniform distribution (T8), and no vegetation cover (control) (T9) were selected. In addition, the effect of different percentages (zero, <40, and 40-60) of vegetation on changes in runoff and sediment components was investigated. It should be noted that the vegetation in the control plots was removed at the soil surface in the desired plots as much as possible. Considering that, 27 field plots surrounded by galvanized sheets with an area of 2 m² with a slope of 12-15% were installed. Study treatments with three replications were designed in a completely randomized block with help of field plots with dimensions of 2*1 m and an approximate slope of 12-15%. This study was performed using a rainfall simulator with an intensity of 32 mm h^-1 and a duration of 18 min. The plots were placed in a rectangular in the direction of the slope, using 15 cm high metal sheets, five cm of which were sunk into the soil so that the generated runoff did not seep out of the plots. Totally, five components including time to runoff, runoff volume, runoff coefficient, soil loss, and sediment concentration were measured for each plot.
3- Results  
The results showed that the effect of different vegetation compositions on runoff and sediment components was significant (p-value <0.0001). The maximum time to runoff (1388.33 seconds) in treatment T4 and the minimum runoff (0.41 L) and runoff coefficient (2.14%) in treatment T2, respectively with +98, -82, and -82 % change compared to the control treatment has been obtained. In addition, the minimum soil loss was equal to 1.30 g in treatment T2 and the minimum sediment concentration was equal to 6 g l^-1 in treatment T8 with -86 and -69% change compared to the control treatment, respectively. Statistical analysis of the effect of different vegetation percent also showed that there was a significant difference between the mean time to runoff and sediment concentration (p-value<0.001) and a non-significant difference between the mean runoff amount and coefficient (p- value<0.73), and soil loss (p-value<0.15). In general, treatments with less than 40% vegetation were more effective in controlling runoff components and treatments with vegetation between 40 to 60% were more effective in controlling sediment components.
4- Discussion & Conclusions
The runoff threshold in different compositions and percentages of vegetation has a significant difference compared to the control treatment. Vegetation in both groups of <40 and 40-60% by delaying the formation of runoff has increased water permeability in the soil. Low-height graminea predominance (T1) treatment, the composition of dense bushes with graminea (T2), bushes with low-height and medium-distribution (T3), and sparse bushes mostly with low and medium height (T4) had the maximum effects (more than 80%) in increasing time to runoff. Although the treatment of the composition of sparse bushes with graminea (T5) was not effective in increasing the runoff threshold and reducing the amount and coefficient of runoff, it reduced the soil loss and sediment concentration by 21 and 57%, respectively, compared to the control treatment. Therefore, it can be concluded that if this type of erosion management strategy is adopted, this type of composition can also be considered. While it is not a suitable management option for runoff and flood control, treatments T4, T3, T2, and T1 should be used effectively. In addition, treatments with <40% vegetation cover had better performance compared to treatments with 40-60% vegetation in improving runoff components; nevertheless, 40-60% of vegetation with a slight difference has played a better role in improving erosion and sediment components. Previous research has confirmed that soil loss processes due to water erosion are closely related to the runoff process. Compared to runoff reduction, vegetation treatments have provided better benefits in reducing erosion and sedimentation. For future studies, the morphological effects of vegetation types on the hydrological and hydraulic properties of degraded soils could be investigated.
 

---

1- Introduction
Sand dunes are one of the most important landforms in arid and semi-arid regions, whose mobility varies depending on climatic factors, especially the speed and frequency of erosive winds, rainfall, and the amount of evaporation and transpiration, which always causes many problems for the activity of these dunes. Therefore, monitoring climatic factors and analyzing dust events can be a positive step toward knowing the factors affecting their activity and predicting their mobility status in the future. Lut desert, with its huge amount of sand masses, is one of the most active places concerning changes in wind speed and direction. The eastern part of this region, which includes the largest sand mass of Iran, the Yalan sand, is dominated by the 120-day winds, which doubles the importance of investigating the winds and their shaping role during the blowing season of these winds. Based on this, the current research was conducted to analyze the mobility of quicksands in Lut plain stations in the past and predict their conditions in the future.
2- Methodology
The study area includes the Lut desert located in Kerman province. To conduct this research, average monthly values of climatic elements including temperature, rainfall, hourly data related to horizontal field of view, wind speed and direction, and the code of various dust phenomena were used. These data were received from the Meteorological Organization of seven synoptic stations that have statistics for 20 years (2002 to 2021). Investigating the changes of climatic parameters over 20 years, investigating the temporal and spatial mechanism pattern of dust, wind and storm rose, calculating the amount of evaporation and transpiration using the Torrent-White method, investigating the condition of dunes using the Lancaster index were the main steps of the current research. The mobility of quicksands was texted using a sensitivity analysis and at the end, the zoning maps of the final sand transport potential were prepared using ArcGIS software.
3- Results
The results showed that the stations leading to Lut plain are facing a decrease in rainfall and an increase in temperature, evaporation, and transpiration. The changes in wind speed are high in Shahdad station and low in Baft station, and the prevailing wind direction in most of the studied stations is west and north. The highest frequency of local and extra-local winds is related to Nehbandan station with 1090 days and Bam station with 791 days, and the lowest frequency of winds is Local and extra-local corresponding to Baft station with 23 and 31 days, respectively. The calculation of the aridity index of the stations showed that the index of prevailing climatic conditions in the region is dry, ultra-arid, and semi-arid due to the activeness of wind deposits and the peak time of local events in the stations located in plain areas, and this means Shahdad station has become a real desert in terms of desertification risk, Baft station is under severe desertification risk, and other five stations are under very severe desertification risk. With the reduction of the UNEP aridity index and the increase of the aridity of the environment, the amount of sand mobility in the whole Lut plain is increased and the risk of desertification in the region is intensified. Based on the sensitivity analysis, if in the future the frequency of winds exceeds the erosion threshold by 30%, the activity and movement of dunes will increase by 30%, while with a 30% increase in rainfall, the dune activity will decrease by 43%. Also, the sand mobility index has a positive relationship with changes in evaporation and transpiration. With a 30 % increase in evaporation and transpiration and the speed of erosive winds, the activity and movement of dunes increase by up to 70 %, and with a 30 % decrease in these two meteorological indicators, the activity and movement of dunes decrease by 50 %.
4- Discussion & Conclusions
By calculating the Lancaster index, the potential activity of dunes has been determined and the active and inactive areas have been separated. The results of the zoning of this index showed that in the studied area, the activity level of dunes is mostly completely active and active at the top of the dunes. It is inactive only in Bam station, which has been done to stabilize and reduce dust activity and management measures such as planting trees, hand-planting desert forests, dunes, and mulching. However, due to the activity of the dunes in other stations, these measures are not enough and need new management and planning. The results of the present research can be used to predict the future condition of dunes and determine appropriate management measures to control and reduce possible damage to other land uses in the region.