مهین کله هوئی

Soil erosion, a significant form of land degradation, poses severe challenges to humanity in different ecosystems. It serves as a comprehensive index for evaluating the development and sustainability of land management programs. Assessing the status and spatial extent of soil erosion has become crucial in developing countries. Biological management, a recommended and effective means of controlling soil erosion in the early stages of all processes, offers a practical solution. Biological methods, such as minimum tillage operations and limited intervention in nature, prove to be more cost-effective and efficient than structural measures. Despite these advantages, biological measures have not received adequate attention in soil erosion control. This research addresses this gap by applying biological management in the Kilanbar Watershed (Kermanshah Province, Iran), demonstrating its effectiveness and cost-efficiency.

The layers of elevation from sea level, aspect, and slope steepness were prepared and combined in the geographic information system (GIS) software to prepare 38 land units. In the Kilanbar Watershed, 14 land units with the ability to perform biological management measures were extracted based on the expert and technical opinions of the watershed manager and considering different bases to improve the performance and decision-making of the units with an area of less than 300 ha. The Kilanbar Watershed is located in Ravansar City, west of Kermanshah Province. The study area is approximately 10798 ha. The highest and lowest elevation points of the watershed are 2183 and 1388 m above mean sea level, respectively. The mean annual precipitation, temperature, and relative humidity are 533 mm, 11.4 °C, and 45.1%, respectively. The status of soil erosion in each land unit was completed based on the scoring of the BLM form based on the visual and expert opinions, and a map of the erosion pattern was prepared in the land units. Ambrotropic and hyetographs were drawn using the 30-year precipitation and temperature data of the Ravansar synoptic station to determine the periods of drought and wet conditions and to identify suitable plants with the characteristics of the region. A climatic–agricultural map was prepared and integrated into the GIS using meteorological station data (temperature, precipitation, evaporation, and transpiration), and plant species were selected according to ecological expectations for watershed biological measures.

According to the BLM form results, one and eight land units are in partial and low erosion conditions, respectively, and five other land units are in medium erosion conditions. According to the erosion pattern map, the majority of the studied area, about 70% of the watershed, is in a low and medium erosion state, which naturally confirms the high ability to use appropriate biological measures to control soil erosion. According to ambrothermic and hyetograph measurements, June to September were dry months, and precipitation changes were more significant than temperature changes from October to May. According to the climatic–agricultural map, the region is divided into five classes. Class 4 (4819.3 ha) and Class 1 (364.83 ha) had the largest and smallest areas, respectively. Finally, the zoning of suitable rangeland species in the watershed showed that rangeland species of Asteragalus ascendes, Avena fatua, Picnomon sp., Achillea millefolium, Bromus tomentellus, and Hordum blubosum dominantly covered the region. Based on the study results, appropriate plant species were introduced for the studied watershed. Accordingly, conservation and reclamation measures were recommended to improve land productivity and ecological conditions and avoid land use changes for the study area. The essential measures include vegetation in rangeland ecosystems aiming at preventing the role of the canopy cover from directly impacting raindrops on the soil surface, increasing water infiltration in the soil, stabilizing soil aggregates due to roots extension, increasing grazing capacity and livestock production, and increasing its efficiency and productivity with time.

The findings of this study hold significant potential for the Kilanbar Watershed. The proposed biological erosion measures, tailored to the ecosystem's unique conditions, are effective, low-cost, and environmentally compatible. They offer a sustainable solution for managing soil and water resources in various ecosystems. Implementing these measures can significantly reduce soil erosion in the watershed, particularly in areas with low to moderate erosion status. This research is an essential initiative in applying biological erosion measures in the Kilanbar Watershed, demonstrating that soil erosion can be effectively and practically controlled in approximately 67% of the watershed through biological methods in the critical land-use areas of rangelands and agriculture. It is important to note that applying biological erosion measures requires comprehensive and integrated investigations, considering the different parts of the ecosystem. With these findings, the proposed approach in this research can be extended to other watersheds across the country, particularly those with slight to moderate erosion status, while maintaining the principle of comprehensiveness and respecting the unique conditions of each watershed.

Soil erosion and sediment yield in the watershed lead to environmental issues. Therefore, knowledge of the spatial and temporal distribution patterns of soil erosion is a proper strategy for planning and prioritize solutions for implementing soil conservation measures at watershed scale. Since biological methods are based on the prevailing conditions of ecosystems, soil erosion can be controlled in the initial stages. However, the biological management of soil erosion has yet to be accepted due to the lack of a suitable implementation model by executive operations. The current research aimed to inhibit soil erosion using biological management in the rangeland areas of the Kojour Watershed located in Mazandaran Province, Iran, due to the predominance of manageable distributed erosion.

For this purpose, the primary layers of elevation above mean sea level, slope, and geology were determined for the Kojour Watershed, and appropriate work units were accordingly delineated. Then, the soil erosion status was assessed on the basis of the scoring table of the seven factors of the BLM model. The study was confined to the rangeland areas based on field surveys, interpretation of satellite images, and expert opinions. In the next step, the leaf area index (LAI) map was prepared to compare field measurements and remote sensing information. Then, Ambrothermic and hytergraph charts were developed, and the corresponding Bio-Climatological map was prepared for the study watershed. Ultimately, suitable species were selected from the phytosociological list considering an appropriate combination strategy of Competitor (C), Stress-tolerators (S) and Ruderals (R), and species.

First, 15 land units were delineated for the entire Kojour Watershed, out of which six rangeland-dominant sub-watersheds were selected to designate the biological management measures for soil erosion control. The BLM table was employed for the rangeland work units showing that three of the six rangeland sub-watersheds were classified as low erosion. The remaining three sub-watersheds also had moderate erosion status. In addition, the general condition of soil erosion in the rangeland areas of the study watershed, with a score of 37.16, is classified as low status. Also, examining erosion maps and the obtained indices indicated a high agreement between field measurements and remote sensing data. According to the Ambrothermic chart, June to September were dry, and August was the driest month of the year in the study area. It also used the scope of significant environmental changes and more uniform regional changes. In this regard, the distribution of the area in the four Bio-Climatological classes of the Kojour Watershed is the same, and it is considered according to the planning and erosion management classes. In the following, the species were selected according to the combined CSR strategy, including Stachys inflata benth, Bromus tomentellus, Artemisia siberi, Trifolium pratense, and Festuca arundinacea with a broad presence in the region.

The present study was conducted to present a biological management model of the rangeland areas for the Kojour Watershed. The results indicated that soil erosion can be efficiently controlled through biological management methods in 40% of the rangeland areas. It is worth mentioning that it uses a model of biological management of erosion, which requires integrated and comprehensive investigations that consider different parts of the ecosystem.

Introduction and Goal:

Understanding the role and influencing factors of soil erosion is crucial for effective management and recognition of erodible land areas. Watershed management is one of the most sensitive and complex types of resource and production management. The fractal dimension can be used to examine the complexity of data and simplify complex natural phenomena. This tool enables generating fractal patterns to assess the morphological behavior and power of watersheds. This research focused on the connection and interplay between the morphological characteristics of the watershed and the fractal dimension in the creation of runoff and sediment.

In this research, the necessary data were obtained from the statistics of the country in the water measuring and observation stations of the watershed. The base maps were utilized to determine the watershed characteristics. The calculation of the fractal characteristics was done in Fractalyse 2.4 software by utilizing the box counting method. The factor analysis method was used to identify 85 features related to watershed. In this research, for further analysis, the size of annual runoff and sediment was investigated using different return periods. Therefore, 5 different scenarios were considered based on the homogeneity of the watershed, climatic characteristics, physical and morphological characteristics of the watershed, physical and climatic characteristics simultaneously, and fractal characteristics of the watershed. The correlation between estimated irrigation and sediment size (with different return periods) and different morphological features was also carried out.

The results of the factor analysis technique showed that among the 85 parameters related to the watershed, 18 are the effective parameters of the area, the slope area is 8-12 and 12-20%, the area of the east slope in 9 directions, the length of the 100-m level lines in the watershed, the total length of the stream , the concentration time base Kirpich method, elevation difference, fractal of 200-m level lines, deviation from the moisture standard, temperature difference, average slope, net slope of the main stream, average temperature, average moisture, average precipitation, elongation coefficient and fractal of the basin environment. Also, the fractal dimension of the 200-m horizontal lines and the fractal dimension of the watershed environment were able to significantly explain the overall changes in discharge and sedimentation. This finding explained well the role of fractal characteristics in the relationship between irrigation and sedimentation.

Conclusions and Suggestion:

Based on the results of this research, it was found that almost all the effective factors in estimating discharge and sedimentation in large watersheds are summarized in the area and fractal of the watershed environment, and these two features justify the most changes in discharge and sedimentation. Therefore, with the reduction of the area of ​​watersheds, the role of other factors such as the direction of the slope, the net slope of the waterway, etc., is more evident in explaining the changes, and it can be said that dividing large watersheds into smaller watersheds is the best measure to control the erosion and runoff of watersheds. Implementing watershed management measures in these small sub-watersheds is the next step. The reduction of watershed area in most relationships is sufficient to justify up to 70% of sediment changes. This research findings should be utilized by users and beneficiaries to implement watershed development and management programs.

The rainfall system of a major part of Iran is mediterranean, where the precipitation amount during the vegetation period is low. In addition, the occurrence of precipitation in the non-vegetation period or beginning of the vegetation period, which does not cover the surface of the earth well, is one of the important reasons for water erosion in Iran. Since vegetation has a special role in soil erosion control and runoff retention, any change in the vegetation structure and pattern, which expresses the landscape pattern and function, can have a significant effect on changing hydrological processes. Therefore, the assessment of soil and water loss and the quantification of its relationship with landscape metrics provide key information for the development of water and soil quality management strategies.

The current research was conducted to investigate the hydrological component changes with landscape metrics on 2 m2 plots using simulated rainfall at an intensity of 32 mm.h-1 in a part of rangelands of Ardabil County. At first, considering the type and percentage of vegetation as the main variable, eight groups of vegetation composition along with one group without vegetation (control) were considered with three replications. The composition (and percentage) of the vegetation from the first to the eighth groups, respectively, include low-height graminea predominance (45), the composition of dense bushes with graminea (43), bushes with low-height and medium-distribution (37), sparse bushes mostly with low and medium height (31), the composition of sparse bushes with graminea (56), dense bushes in upper parts (54), low-height bushes with very low distribution (15), and dense bushes with almost uniform distribution (56). After measuring the runoff and sediment at the plot outlets, different hydrological components were calculated. Then, plots with nine different vegetation combinations were imaged in three replicates before and after rainfall simulation. After transferring the images prepared from the plots to the Arc/Map10.8 environment, nine important landscape metrics were calculated.

Changes in the mean patch density (4.43-26.90), largest patch index (54.16-86.75), edge density (17.12-107.38), landscape shape index (1.50-4.47), mean shape area (4.16-37.46), mean Euclidean nearest neighbor distance (0.00-1.65), landscape division index (0.19-2.31), mean patch shape index (1.24-22.85), and the effective mesh size (15.80-43.96) indicate their different influence from different percentage and composition of vegetation cover. Spearman's correlation matrix analysis showed a nonsignificant relationship between the mean soil loss, runoff volume, runoff coefficient, and sediment concentration with landscape metrics (r<0.26 and p-value>0.10). The small scale of the studied plots, the lack of diversity in the vegetation composition, and the uniformity in terms of vegetation height can be cited as the reasons for the lack of correlation. In general, groups with vegetation values above 50% had a better condition in terms of LPI, AREA_MN, and MESH, which indicates more connectivity and less degradation. The increase in vegetation cover and spatial heterogeneity above the landscape surface can change the path of sediment transport, reduce sediment connectivity, and lead to a decrease in sedimentation.

The obtained results are applicable in explaining the appropriate reference to optimize water and soil protection measures on the watershed scale. However, It is suggested that similar and more comprehensive research be done in different scales of erosion plots and even in the landscape (slope) scale so that by considering a wide range of vegetation, topography, climatic conditions, as well as successive rains, it is possible to compare the results, optimum selection of study scale, and finally planning to manage and protect vegetation and water and soil resources.

Statement of the Problem: Floods are a devastating natural disaster that can cause soil erosion, soil wastage, and damage to human infrastructure in flood-prone areas of watersheds. Therefore, it is crucial to predict and determine the amount of runoff production processes and its safe transfer to the outlet of the watershed. Various factors, including climatic and physiographic parameters, affect the conversion of precipitation into runoff. Climatic factors involve the intensity and duration of rainfall as well as the distribution of rainfall locations. Physiographic parameters include land use type, soil type, watershed area, basin shape, height, slope, direction, and type of drainage network. Therefore, several methods can be used to estimate the runoff generated by rainfall, and one of the commonly used methods in hydrology is the Soil Conservation Service (SCS) method. Furthermore, determining the spatial changes and correlation between the factors of runoff production and flooding can identify flood-prone areas. Therefore, this research utilized geographic information systems (GIS) to provide essential and fundamental information for obtaining direct runoff using the curve number (CN) method. The study aimed to estimate the height of excess rainfall runoff and analyze the spatial variations of runoff height and volume in the Sharganj watershed, Birjand. To achieve this goal, the SCS method was employed to estimate the amount of runoff generated by the maximum 24-hour rainfall in different return periods in the aforementioned watershed. Subsequently, the changes and spatial correlation of the values of the height and volume of the runoff were evaluated in the Sharganj watershed, Birjand.

This study estimated the amount of runoff produced from the maximum 24-hour rainfall in different return periods in the Sharganj watershed using the SCS method. To achieve this, the maximum 24-hour rainfall from surrounding stations was averaged using the IDW method. Next, the SCS method was utilized to estimate the runoff by combining land use maps and soil hydrological groups to prepare the curve number map. The basin runoff volume was then calculated for different return periods. Additionally, the spatial autocorrelation of the runoff height and volume in the 25-year return period was analyzed using the general Moran's index, and their clustering pattern was determined using Anselin Local Moran's Index.

The Sharganj watershed is primarily used for pastures and agricultural lands, with the former being located in hydrological group C. Despite this, rainfed and irrigated garden lands, mainly located in hydrological group B, have better permeability. Using ArcGIS software, land use maps and soil hydrological groups were combined to prepare a curve number map of the watershed. The results showed that the curve numbers of the sub-watersheds ranged from 68 to 79, with sub-watershed number 9 having the lowest curve number value (68) and sub-watersheds 22, 25, and 29 having the highest (79). The Global Moran's index values presented in Table 3 and Figure 10 showed that the spatial correlation of runoff height and volume had values of 0.1828 and -0.2694, respectively. The curve number decreased from west to east due to the presence of barberry gardens and irrigated agricultural lands. The spatial correlation map of runoff height values showed high-high (HL) clusters forming in the upstream parts of the basin, while low-low clusters (LL) were present in the downstream areas. These patterns were related to the amount of precipitation in the upstream part and the high slope of the upstream sub-watersheds. Meanwhile, the spatial correlation values of runoff volume indicated that the accumulation of runoff volume was higher in the sub-watersheds located downstream of the study area, with low formation of high-low (HL) clusters. This increase in flood volume occurred in the downstream sub-watersheds and adjacent to the outlet of the area. In general, the difference in the cluster pattern of runoff height and volume did not follow the same pattern, which depended on various factors affecting runoff production, such as the amount of precipitation in different parts and the difference in topography. It should be noted that the analysis was based on height and volume values in the 25-year return period, and the results can be expected to be similar for other return periods based on the curve number method.

The research findings suggest that the spatial changes in runoff height and volume components, which impact watershed response and flood producing procedures, are determined by various factors such as slope, land use, curve number, and soil hydrological group. Areas with high amounts of runoff are more susceptible to damages caused by floods and can be prioritized for management measures. Furthermore, the results indicate that the type of surface runoff control measures or flood volume control required will vary, providing valuable guidance for determining the appropriate damage reduction operations. Further studies analyzing the spatial correlation of height and runoff volume variables with other basin features and climatic factors could enhance the understanding of spatial changes. The formation of surface runoff is influenced by various factors related to rainfall and ground conditions, which could be considered in future research.

Today, the destruction of natural resources is one of the most important and serious challenges facing development programs. Soil erosion is among the processes that directly and indirectly threaten our country's soil and water resources. Water erosion appears on the earth in different forms, one of the advanced forms of which is the gulies. Gully erosion is one of the important processes of soil destruction, which in different climates causes significant soil losses and the production of large amounts of sediment. The purpose of the present research is to investigate the morphological characteristics of the gullies of Khuzestan province and the role of its influencing factors in the expansion of the gully areas.

 First, by collecting available data and comparing it to satellite image and other data, the province's gullies have been defined. The first field visit focused on verifying the integrity of these areas and correcting the gullies boundaries. The total area of Khuzestan province approximately is 64000 km2 in the dry desert climate, and more than 33,862 ha of it is under the influence of gully erosion. The hot semi-arid climate also covers approximately 12,1% of the province and 16,116 ha have experienced gullies erosion. After determining the area of gullies and dividing the areas above and below 500 ha, due to the difference in appearance, topography, and vegetation, 2 and 1 representative areas were selected from the hot-dry desert and hot-semi-arid climates, respectively, and 2 replicates were selected from each representative. Longitudinal and cross-sectional profiles of representative and replicated gullies were drawn and after soil sampling, all morphological features of the gullies were measured.

According to the results, most of the gullies of the province have been created in the plains with a low slope with deep soil and loamy sand texture, silt or silt loam with pasture, and sometimes agricultural land and U-shaped cross-section. Darkhazine and Sharif gullies, with 1260 and 912 cm, and Darkhazine gullies with 420 cm value have the maximum width of top, bottom and depth in the cross-section of 75%. Also, the gullies of Choghazanbil, Darkhazine and Choghazanbil with values of 30 cm have the lowest depth, top and bottom width in the cross-section area of 75%. The overall profile is scratched, and in terms of depth class, they are in the category of medium-deep gullies with a vertical top.

Intrinsic characteristics of soil, formation and geological type, climate, intensity of rainfall as natural factors, and destruction of vegetation, land use change and the lack of proper management, unprincipled road and bridge construction operations, construction and installation of oil facilities and electricity bars as human factors have played a role in the process of gully expansion. However, the diversity and change of the number and degree of influence of different factors from one point to another and the difference in their participation in the formation and expansion of the gully are based on the environmental conditions of the land. These conditions require that more research be carried out to identify as many factors as possible in the phenomenon of gully erosion and their participation in the formation and expansion of this phenomenon in different places and with different environmental conditions.

The sudden increase in population growth, followed by the restriction and scarcity of the world's supply of freshwater resources, has created new conditions for countries in the arid and semi-arid belts. To conserve, enhance and make the best use of these valuable resources, several projects have been implemented, including irrigation and drainage, flood control and dam construction. Meanwhile, dams are a very important tool to manage the river water for socio-economic development and also to improve the deteriorated ecological status of the river system and its services. Depending on place and time, dams play both negative and positive roles in environmental flows, with significant environmental costs. According to the results of the documents and reports, the construction of the dam has brought about environmental changes from various aspects of invasion and increase in invasive species to improving access to spawning habitats for migratory fish. The challenge for managers and scientists today is to better understand and manage the consequences of dam decommissioning. For this reason, the purpose of this study is to present the approaches of removing the dam on ecological changes. The results of this research can provide stakeholders in the responsible departments with valuable information about the changes in the behavior of dams on the environmental properties.

Watershed health provides an integrated view of the factors influencing the watershed conditions. In the current study, the data length effect on changes in SPI-based watershed health index was evaluated using the RelResVul framework for the period of 1961-2021 in Sahneh, Kermanshah, and Harsin stations in Kermanshah Province, Iran. For this purpose, reliability (Rel), resilience (Res), vulnerability (Vul) indicators, and mean watershed health (RelResVul) were calculated in different periods. According to the results, watershed health indicators were different in 1961-1980, 1981-2000, and 2001-2021. In addition, with the increase in the length of the statistical period, health indicators had different changes, so that in short-term data, the changes of the indicators mentioned above were more than the whole period. The maximum changes in the first 30 years of the statistical period, and with the increase in the length of the statistical period until the end of the period, changes decreased. Accordingly, the last 30 years of the statistical period have reliable results in calculating health indicators. Considering massive calculations, climatic data deficits, and limited stations while increasing the length of the statistical period, it is suggested to use the climatic data of the last 30 years to estimate watershed health.

Soil erosion is considered as one of the critical threats to the conservation of water and soil resources. However, until now, its various components, including its spatial changes, have yet to be given due attention. In order to implement soil erosion control and conservation programs in the watershed, it is essential to have basic information leading to know and accurately identify the factors affecting the degradation of soil and water resources. Meanwhile, the CORINE model has been considered as one of the practical models for estimating soil erosion and displaying the spatial distribution of soil erosion with easy and accessible inputs. The CORINE model developed based on the Universal Soil Loss Equation (USLE) was therefore employed in the present study in the GIS environment to determine the potential and actual erosion risks of the Brimvand Watershed in Kermanshah Province, Iran.
 

The main associated factors of soil erosion, viz. soil erodibility and erosivity, such as slope, vegetation, depth, texture, and percentage of gravel, were collected, compiled, and ultimately classified in the ArcGIS software. The Fournier index (FI) and FAO-UNEP drought index (DI) were used to prepare the input maps. The Fournier index reflects the performance of the soil erosive agent. In other words, it shows the role of rainfall on soil erosion. The FAO-UNEP drought index shows the simultaneous performance of evaporation and precipitation on soil erosion of a region. The potential soil erosion risk was obtained by combining slope, erodibility, and erosivity layers. In addition, the actual soil erosion risk map was determined by combining the vegetation map and potential soil erosion risk.
 

Based on the results of the vegetation distribution in the region, the use of rainfed and abandoned lands had the largest area in the watershed, with an occupation percentage of 65.48%. Furthermore, the rangeland and forest areas, with respective coverage of 29.65 and 4.87%, stood in the second and third priority from the viewpoint of the area. The region has varying slopes, but more importantly, it has a low slope. Soil texture, depth, and gravel content significantly affect the area's erosion. The soil depth in a large part of the watershed, especiallywith a slope of less than 4% is more than 65 cm where it is mainly covered by abandoned and rainfed lands. In the studied area, the depth of the soil decreases with height increase, which indicates that the high slopes of the area are dominantly outcrops. Most of the area has gravel contents between 10 and 40%. The erosion potential of the region is not that much high because of the desired features of the affecting factors. According to the potential soil erosion risk, it was determined that about 65.57, 23.62, and 10.81% of the area were classified as intermediate, low, and high erosion potential, respectively. Further, the actual soil erosion risk was categorized as low, intermediate, and high with respective areal coverage of 53.83, 15.53, and 30.64%. It is therefore implied that the amount of erosion and sediment transfer will increase if the land cover in the watershed is declined.  This indicates that the erosion rate was highest in hilly areas due to lack of vegetation and soil with loamy texture. Accordingly, to curb soil erosion and prevent its associated adverse effects in the Brimvand watershed, it is strongly suggested to use lands based on their capability and potential, maintain the present cover status, and carry out management plans to restore vegetation.
 

Soil erosion remains one of the most critical challenges in watersheds, and its neglect can lead to various problems for the beneficiaries. In light of this, the present study aimed to address this issue by employing the CORINE model to assess potential and actual soil erosion in the Brimvand Watershed of Kermanshah Province, Iran. The research findings reveal the pivotal role of vegetation in mitigating soil erosion. Notably, areas with gentle slopes, which are inherently susceptible to erosion, benefit significantly from vegetation cover, leading to a noticeable reduction in erosion. However, the loss of this protective cover can trigger a rapid increase in soil erosion and subsequent loss of valuable soil resources. By shedding light on the spatial distribution of soil erosion, this study emphasizes the importance of preserving and promoting vegetation in the watershed to ensure its long-term sustainability and safeguard the well-being of those who depend on it. Therefore, land utilization should be planned based on capacity and potential of the land to curb erosion and avoid its detrimental impacts in the Brimvand Watershed. In addition, not only the current cover situation has to be maintained but also the vegetation conditions have to be improved through the implementation of managerial and reclamation plans leading to managing soil erosion.

The present study was conducted to conceptualize and evaluate the health of the Asiabrood Watershed in Chalus Township, Mazandaran Province, Iran.

The existing regional data, including climatic, hydrologic, erosion, sedimentation, and economic and social data, were collected and analyzed. In addition, several field visits were also made to make a general assessment of the ecological, economic, and social situation of the region and to complete the information on the study watershed. Then, the watershed health was assessed using the conceptual model of pressure, state, and response at the sub-watershed scale. Accordingly, the pressure index was first investigated by analyzing the driving forces of human activities and climate change over the study watershed. Then, the current state of the natural environment and the watershed performance to the pressures was analyzed as the status index. Further, the response index of the Asiabrood Watershed was calculated as a criterion for expressing the degree of community response or different outcomes of the watershed to the changes and concerns imposed on the watershed system.

 The results showed that the total health index of the Asiabrood Watershed with respective and relative contributions of pressure, state, and response indices of 18, 39, and 43% and an overall health index of 0.50 has a moderate health condition.

Although the health status of the Asiabrood Watershed is in moderate condition, the health status of the study watershed may decline, and, of course, adverse responses are possible if appropriate management policies are not adopted.

Gully erosion affected by many factors causes the destruction and loss of large volumes of soil along with great economic and social damage. The variability of diversity, the number and size of the influence of different factors from one point to another and the difference of their participation in the formation and expansion of gullies is based on the conditions of the land. Such conditions have caused more researches to be carried out to identify as many factors as possible in the phenomenon of gully erosion and the extent of their participation in the formation and expansion of this phenomenon. In this regard, the present study has been planned with the aim of monitoring and evaluating the effective factors in the development of gullies in the Haddam and Sharif watersheds of Khuzestan province. Modares Shushtar watershed, having Sharif and Hadam subwatersheds, as one of the important and typical basins of the province, every year a large area of its agricultural land is threatened by gully erosion.

In order to carry out this research, first, the parts with gullies in the study area were identified on the topography map with a scale of 1:250,000 during the 20-year period (1993-2012). Then, 15 gullies have been identified and investigated from each climate class of hot-dry desert and hot-semi-arid. Features such as the slope of the initial point of creating a gully and the slope of the front of the gully were calculated by the field method and using a tape measure, level and inclinometer measuring device and the mirage area of the gully front in the Google Earth softwave. Also, the physical and chemical characteristics of the soil of each gully were tested.

The results showed that the average percentage of bare soil above the head cut of selected gullies in Haddam and Sharif watersheds is 99.8% and 97.26%, respectively. Based on soil characteristics, the main cause of soil instability and erosion in gullies in both watersheds is EC. The morphometric characteristics of the gullies showed that in the Haddam watershed, all gullies are V-shaped in terms of cross section, and in the Sharif watershed, only gullies are B12, V-shaped and the rest are U-shaped. The Haddam watershed has the highest depth, width, and top of the gully compared to the Sharif watershed. The total volume of soil loss in Sharif and Haddam watersheds is 23000 and 51579 m3, respectively. Gullies A18 and B1 in Haddam watershed have the highest and lowest soil loss volume, at 11599 and 1612 m3, respectively. In the Sharif watershed, the maximum and minimum soil loss volume of gullies related to gullies A2 and B4 are 5282 and 369 m2, respectively.

Conclusion and Suggestions  :

The most important factors in the volume of soil loss and expansion of gulies are the characteristics of the watershed located upstream of the gully front (such as the extent and slope of the watershed) as well as the fineness of the geological formation (silt) and high soil salinity. Due to the excessive bareness of the soil, increasing the roughness of the soil surface with the establishment of vegetation is one of the compatible and low-cost methods in protecting soil resources. In order to control the spread of gully erosion, it is necessary to increase soil organic matter, modify saline and sodium soils with the use of modifiers, and also divert the runoff from the gully front.

Today, soil erosion has become one of the most severe problems in the world, especially in arid and semi-arid regions, affecting environmental, agricultural, and food security. The growth and development of human activities, land-use change, and resource degradation are among the factors affecting erosion intensity. However, preventive approaches based on soil erosion risk assessment have received less attention to taking proper management measures. Due to the importance of preventive measures and soil erosion control, this study was conducted in the costal Sourak Watershed in Hormozgan Province using the ICONA model to investigate erosion risk and identify erosion-sensitive areas.

The information input layers of steepness, rock surfaces and land- use are overlapped for the employ of this model in the study watershed. Soil erodibility risk map was also developed using complying soil erodibility and soil conservation maps.

The results, besides prioritizing sub-watersheds, portrayed the erosion risk at different levels of very low, low, moderate, high, and very high with relative area extension of less than one percent, 31.08, 23.28, 12.01, and 28.67%, respectively.

The findings of the current research, in addition to confirming the ability of the applied model to estimate the risk of soil erosion in the study watershed, emphasized the possibility of using the erosion risk map as a suitable tool for managers and executive experts in the effective management of water and soil in the region.

The purpose of this study is to identify the shape of ruggedness, activity, physical-chemical and mineralogical characteristics of sands in Kermanshah province. The results showed that the most important form in the desert lands of the study area is the sand arrow and the degree of activity of the sand dunes is semi-active and most of them are unstable.

Today, new patterns of planning at the watershed level have found a valuable place in order to implement collaborative projects. Planning in watersheds with the participation and partnering of regional stakeholders in the process of preparing and implementing plans can be an effective step in increasing the sustainability of the region. Collaborative approaches must be fully aligned with the knowledge, experiences, values, and interests of the various stakeholders. This study is planned with the aim of taking advantage of the perceptions and approaches of the residents of the Mohammad Abad Ganbaki watershed, Kerman, in order to find optimal strategies for the management of the watershed. For this reason, in the upcoming study, it shows the importance and necessity of SWOT analysis to combine the preferences of stakeholders in the decision-making process. For this purpose, the current study has been carried out in three stages, listing the internal (strengths-weaknesses) and external (opportunities and threats), preparing the assessment matrix of internal (IFE) and external (EFE) factors, and preparing the quantitative strategic planning matrix (QSPM). The results showed that the production pole of citrus fruits and dates in the country with a weight of 0.444, the existence of dust centers in the region with a weight of 0.198, the potential of electricity generation from the Nessa Dam with a weight of 0.384 and a one-dimensional economy based on date production with a weight of 0.247 are the most important strengths, weaknesses, opportunities and threats of the region. The high potential of the region in creating early productive commercial workshops according to the existing conditions through the possibility of raising honey bees with the presence of citrus fruits, the possibility of reviving handicrafts, increasing agricultural production and medicinal plants, creating a greenhouse with hydroponic cultivation and fish farming, the possibility of reviving the animal husbandry industry, providing date and citrus packing and processing centers are the most important strategy in the field of providing a job market for young people, reducing economic poverty and migration of residents.

Gully erosion contributes severe land degradation. It is therefore, necessary to identify the aggravating factors and to provide for sensitive areas to gully development. The aim of this study was to determine the spatial and climatic distribution of gully in Kermanshah Province, Iran and to identify the morphological characteristics and the main factors of their development. First, using 1: 20,000 and 1: 50,000 aerial photographs, the predominantly gully areas of the province were identified and then this information was corrected using field suevey. The climatic zones of the gully areas are identified using existing maps and modified by the Domarten Method. In each climate, one to three gully areas were identified as targets and in each of them a gully was identified and two replications were identified. The gully chanel chrectreristices were location, landuse, dimensions at the head-cut, intervals of 25, 50 and 75%, slope, width, length and cross section. The results showed that 17% of areas in the Kermanshah Province was affecterd by gully erosion comprising eight sub-climate classes. Dominat topographic conditions of gullies were developed at hilly and gentle plain areas with Trapezoidal cross section. The cross section indicated deep and V-shaped gully in marl formations (Fars group). These areas included Sarfiroozabad, Somar and Jabbarabad where most of gully measures were deeper and wider than other parts. Among the effective factors in creating and expanding the gully, we can mention heavy rainfall, slope, soil erodibility and destruction of vegetation upstream of the basin as natural factors and change of land use and improper exploitation as human factors in developing gully erosion.

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.  

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.

 

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.

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.

Today, water resources have become one of the major concerns in arid and semi-arid regions of the world. Low rainfall and its irregular distribution in Iran, along with rapid population growth and increased agricultural activities, have caused recent droughts. The present study was conducted with the aim of investigating and forecasting meteorological drought in Tehran province using the ARIMA model. Data from seven rainfall stations for the period 2000-2020 were used to evaluate the Standardized Precipitation Index (SPI). Then, the ARIMA model for drought prediction was implemented based on SPI, and the best model for drought prediction was extracted for each station. The results showed that ARIMA time series models can correctly evaluate climate change. Also, according to the results of the SPI drought index for the forecasted period, it was found that the situation was close to normal in all the studied stations, and from 2022 to 2024, the conditions have progressed towards improving the rainfall situation, which according to the recent rainfall in Iran, this model It has been able to model climate changes well. According to the SPI index, the drought in the target area is close to normal, it can be a suitable tool for managing water resources, preserving natural ecosystems, and improving the future climate.

Watershed management in Iran requires a new attitude toward its management patterns. The implementation of existing sectoral policies in the country has increased the pressure on the quality and quantity of valuable natural resources. However, in the current situation, the country's watersheds, with their current management patterns, are still in unstable situation.The existing management challenges suggest the fact that watershed management is still facing a major crisis in Iran and has not been able to improve the health status of watersheds. Structural weakness of organizations, weakness of rules, lack of evaluation, monitoring and accurate monitoring can be the main root of these problems. Therefore, the main purpose of this paper is to address the necessary to conceptualize integrated watershed management approaches by collecting available documentation and findings. Then, the structure and administrative framework with appropriate strategies have been formulated based on identifying effective factors in the success and failure of managerial patterns. Changing the attitude from an island approach to an integrated approach in watershed management, increasing the internal and external cohesion of organizational structures, utilizing stakeholder participation-oriented management models and formulating relevant supporting laws are effective factors in the effective implementation of integrated watershed management. Increasing the sustainability, resilience and health of watersheds depends on the implementation of the principles of integrated watershed management.The achievements of this study can be a clear policy for managers and politicians in the country's natural resources.

Given the importance of soil and its significant role in the countries evolution, numerous methods are presented to preserve this national capital and to combat the soil erosion consequences. In recent years, Iran like other countries, has taken an effective step to protect soil using organic and inorganic soil preservatives. Therefore, the aim of this study was to investigate the effect of corn mulch on rate and changes runoff and sediment.

This study was in loam – sandy soil in scale small plots laboratory and using a rain simulation with an intensity of 50 mm / h with a10-minute duration has been done. For this purpose, three levels of protective cover of 25, 50 and 75% of corn mulch one control treatment (without conservation cover) with four levels of moisture, air dry, 15, 20 and 30% were considered in three replications.

The results of this study showed that application of corn mulch has a significant effect on runoff and sediment reduction at 99% level. Considering the moisture levels, the amount of runoff and sediment yield in uncoated (control) and 25, 50 and 75% plots were 4422, 4290, 3943 and 3619 ml and 296, 136, 62 and 33 g, respectively. The results of percentage change of runoff, sediment and start time of them showed that the cover at 25, 50 and 75 percent protective cover and different moisture levels were 3.14, 11.25 and 19.29 percent, respectively. Sediment reduction was 62.06%, 77.09% and 88.85%, respectively, compared to the control treatment (without protective cover). The percentage of changes in runoff and sediment of them increased by 32.23%, 73.38% and 136.82%, respectively.

Based on the changes in hydrograph and sediment graph, it was found that 75% corn mulch at 15, 20, and 30% moisture content at 645, 452, 215 and 99 seconds, respectively, was more effective in increasing runoff and sediment time to runoff compared to the control treatment other cover surfaces have been used. However, two more (25 and 50%) were also effective in increasing production time to runoff and sediment. knowledge the trends of runoff and sediment changes and their time by applying conservation cover can be a useful tool and effective solution for soil and water conservation.

Gully erosion is one of the main sources of soil loss in watersheds and also one of the main causes of sediment storage in dam reservoirs and river alluvium. In addition, human activities can exacerbate this erosion, which has very worrying consequences. Therefore, the present study was conducted to determine the environmental thresholds of gully erosion and also the morphoclimatic classification of these areas in Kermanshah province.

To do this, first by collecting information from relevant authorities and also using aerial photographs 1: 20,000 and 1: 50,000, the main gully of the province that were visible on the pictures and then this information using field operations and specifying them on corrected on topographic map. Climatic zones of gully in the province were identified using existing maps based on the modified Domarten method. Then, in each climate, one to three gully were identified as targets, and in each of them, a representative gully was identified and two replications were identified, and the field identification of these gully was completed by field operations and field visits. These characteristics included location, land type, dimensions at the head of the gully and at intervals of 25, 50 and 75% of the top, length, profile and general plan of the gully. In addition, soil sampling was performed in the above sections and some physical and chemical properties of soil were measured in the laboratory. The classical statistical method of cluster analysis was also used to classify gully.

The results of this study showed that there are differences in the important morphometric characteristics and topographic threshold of the studied gully in different gully in the province and in different climates, which are mainly due to the climate, type of formation, topography and vegetation of this area. Classification of gully based on the classification method showed that with a similarity level of 97.5%, three general classes can be identified for gully.

gully areas in arid desert climates (warm regions) of the province in one class, gully zones located in the middle altitudes and cold semi-arid climate in the second class and gully zones in cold semi-arid climates to the Mediterranean colds are in the third class similar to gully. The active gully of the province are mainly located in the hill and plain lands. The results of this study show a picture of effective and influential factors in creating gully, based on which it is possible to apply how to control them in future planning and management of officials.

Water and wind erosion is one of the most important causes of soil loss. Understanding these interactions is essential for estimating soil quality and environmental impacts in areas with both types of soil erosion. Numerous factors affect the occurrence and process of water erosion. In this regard, dynamic climatic factors such as rainfall and wind have the most prominent role. Accordingly, water erosion control will be effective when sufficient knowledge is available about the effective factors. In this regard, the present manuscript has tried to address this issue from a different perspective and discuss the effects of different climatic factors on water erosion by analytically reviewing existing literature. The results of the review showed that among the climatic factors affecting water erosion, the role of rainfall on runoff production and soil loss had been paid more attention, and the role of other variables such as wind on behavioral changes in water erosion has not been considered. While in the presence of wind, the behavior of raindrops is changing and undoubtedly affects the process of water erosion and hydrological components. Changes in droplet diameter, velocity, angle of attack, and kinetic energy of rain can play an essential role in changing water erosion, especially splash erosion. However, accurate identification of effective and influential factors can provide beneficial analysis to experts, managers, and executives for modeling and ultimately proper management of the water erosion process.

The present research aimed at presenting a new SWOT strategy for integrated watershed management of Asiabrood in Mazandaran Province. At first, the SWOT matrix and the tables identifying the strategic indicators of internal and external factors were formed and then internal and external evaluation matrices were analyzed. A new strategy used in the discussion of the weighting of SWOT strategies was based on the fact that the final value of each strategy was multiplied by the number of effective strengths and opportunities and the final results were analyzed based on these priorities. Based on analysis of strengths and weaknesses, nine strengths and eight weaknesses were identified. The suitable water quantity and quality with a weight of 0.444, low air temperature with a weight of 0.395, mineral water utilization with a weight of 0.288 and economic poverty with a weight of 0.493, respectively, were the most important strengths, weaknesses, opportunities and threats. According to the internal-external factors evaluation matrix in the SWOT model, the strategy of increasing the sense of satisfaction of residents, based on the conventional method and the new strategy, gave the highest value. With a careful look, it can be concluded that strengthening the sense of satisfaction between residents happens when People problems in different sectors of livelihoods, including economic, social and cultural, have been considered more and, by presenting correct programs, have increased satisfaction and reduced migration to urban areas. In general, it can be concluded that due to the problems and solutions presented in this study, proper and applied planning should be used to compensate for the weaknesses and to strengthen the strengths as much as possible in the development of Asiabrood watershed.

Water balance and flow analysis within a basin is particularly important in terms of water development and utilization programs. Therefore, the purpose of this study is to evaluate and predict the outflow rate of Baghan watershed in Bushehr province. The data required for the implementation of the rainfall and discharge models were used to obtain the precipitation data of the Baghan Meteorological Station and the discharge of Baghan Hydrometric Station from 1981 to 2010. The Salas model is derived from a number of simple sub models that characterize different flow processes in the basin such as surface runoff, infiltration, evapotranspiration, deep infiltration and base flow. Error squares were used to calibrate the function model. The results of this study showed that the highest amount of rainfall in the basin was evacuated from the basin by evapotranspiration. The results showed Relative root mean square error before and after optimization of the coefficients of the four-variable Salas model decreased from 2.18% to 1.5% and the mean absolute error from 10.13 to 0.73. and mean error of the Salas four-variable model showed that in the years when the discharge value is almost average, the simulation value is very close to the observed value, and when the discharge value is much higher than the normal years, the simulation value is the less than its observed value.

In forest ecosystems, vegetation characteristics along with climatic parameters have a great influence on the distribution of precipitation components and water cycle. The present study was therefore conducted to measure the amounts of interception loss, throughfall and stemflow in Quercus castanifolia, Ulmus glabra and Parotica Percica at the campus of Faculty of Natural Resources of Tarbiat Modarres University, Noor, as representative of Hyrcanian forests of the country. Precipitation measurements were carried out by 23 collector containers over the course of a year from 06/10/2018 to 06/10/2019 with 34 storm events. The results showed that the rates of steamflow in Quercus, Parotica and Ulmus species were 0.97, 0.56 and 0.34%, respectively. There was a strong and positive and linear relationship between steamflow and precipitation in the Parotica type (R2 = 0.70). The interception losses were also 19, 17 and 8% in the Quercus, Ulmus and Parotica species, respectively. Regressions were also satisfactorily established between total precipitation and mean interception loss with coefficient of determination of 0.61, 0.62 and 0.46 for Quercus, Ulmus and Parotica stands, respectively. The results of ANOVA verified no significant difference between interception loss (P = 0.790) and throghfall values (P = 0.894) among the three study species. However, there was significant difference (p=0.015) between the moisture contents of litters in Quercus sp. compared to other two types of Ulmus sp. and Parotica sp. There was also significant difference between the values of Quercus sp and Ulmus sp (P = 0.009).

Flood is one of the most important hazards that many human and environmental factors can cause. water years 2017-2018 and 2018-2019 are drought and tragic, respectively, during the recorded statistical period of the country is very low. In the water year from 2018 to 2019, as of the date of 09/04/2019, the average difference of rainfall in the whole country with a similar situation in the last year and the medium-long term was 181 and 46 percent, respectively. In the meantime, surveying statistics and flood-related causes can be useful in providing a true and realistic view of policy-makers and decision-makers to make future decisions to prevent similar occurrences. In this research, in particular, the flood of Golestan province was investigated by studying the sources, documentation and reports related to the causes of recent flood events in the country (late March, 2018 and the first half of April, 2019), which resulted in the most important and effective reasons of the flood. Submission of practical suggestions was made in order to adapt management solutions.