s.h.r. sadeghi

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.

Soil erosion and its consequences are the main problems to the development of the country. Achieving sustainable development is not possible without the conservation of soil and water resources and reducing land degradation. However, most soil and water conservation methods are engineered regardless of biological methods' capabilities to control soil and water loss. Therefore, in the present study, an attempt has been made to review the performance of soil microorganisms as a biological method in soil and water conservation on the practical components in soil and water loss in the soil erosion process as a review study. The review results showed that the cyanobacteria, bacteria, and fungi in the soil are effective in inhibiting the process of erosion and runoff by improving soil stability components. Therefore, the empowerment of soil surface against the erosion of rain and runoff with soil crust development reduces and inhibits soil erosion. The use of soil microorganisms can be used as an effective and compatible solution with ecologists of watersheds in the implementation of management proceeding to conservation the soil and water of the country.

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.

Nowadays, natural disasters and human interventions are the main causes of problems at the watershed scale, hence, the management of such challenges is considered as one of the major problems. However, the present approaches for the management of the watershed resource do not appropriately handle the current issues. So that the scope and type of environmental issues are ever increasing and stand beyond the ecosystem tolerance. As communities strive for recover from disasters and move forward, resilient watersheds facilitate better management of natural systems against future hazards. Towards this, the resilience assessment approach has been proposed as a novel approach using existing potentials and pertinent definitions, indicators, and measurement patterns to strengthen multidimensional systems such as watersheds. Since the application of resilience analysis approach in dynamic and complex, it has not been conceptualized and reported until now in watershed systems. Accordingly, the present endeavor is an attempt to conceptualize the resilience of watersheds in order to provide a useful perspective for understanding management decisions and changes related to natural resources in the context of comprehensive watershed management.

The lack of sustainable management of natural resources is one of the fundamental challenges to which societies and governments are faced and should be therefore addressed more seriously in the future. Hence, effective management of nature and environment requires a coherent and a knowledge-based structure, enough, reliable and up-to-date information. Accordingly, adaptive management is a landmark to achieve sustainable resource management. However, applicability of watershed adaptive management has not been assessed yet. The present study therefore aims to apply the watershed adaptive management consists of identifying the problems, designing, implementing measures, monitoring, assessing the ecosystems conditions and finally adjusting approaches. It is further planned to develop appropriate conceptual model for the adaptive management at the watershed scale. The performance will be then compared to that of the application of conventional measures. Towards this, the details of different sectors of adaptive management will be designated based on scientific standards and bases. Accordingly, assessment of watershed health, diagnosis of appropriate strategies, implementation of low impact and best management practices and ultimately performance evaluation will be taken place in the present Study.

The purpose of this study is to assess Farmers’ attitude toward the soil conservation practices in the Kushk-Abad catchment basins in the province of Khorasan Razavi. A sample of 200 farmers was randomly selected from 1200 farmers living in Kardeh catchment basin. Data collection was done through a questionnaire that was administered in 2014. Validity of the questionnaire was confirmed by a panel of experts. To assess the reliability of the questionnaire, Cronbach’s alpha was used. This coefficient for adoption level of sustainble soil conservation practices was 0.84. The data were analyzed using descriptive and inferential statistics such as extent of mean, standard deviation, coefficient of variation, correlation analysis. The results showed a medium level of soil conservation use by most farmers. It was also found that there is a significant positive correlation between the amount of communication channels, information resources, and access to the IT infrastructures use with our dependent variable i.e. soil conservation implementation. The hierarchical regression analysis was applied in two steps to determine the predictive variables of soil conservation practices which, at the first step, the variables pertaining to the amount of communication channels and information resources were entered followed by variables of access to the ICT infrastructures on the second step as the independent variable.

Infiltration is one of the most important soil physical variables and basic data in rainfall–runoff models for water loss determination in watersheds. Its measurement is، however، time consuming and costly. For this reason، soils infiltration rates determination by different models is always a serious concern to researchers. In this research، a single event precipitation was measured using rainfall simulator during a 90-minute rainfall for determination of the best infiltration equation in watershed scale. The parameters of five infiltration models namely Kostiakov، Green-Ampt، Horton، NRCS and Philip، were estimated by sum of squared error optimization for four different land uses and three soil textures of sandy clay loam، loam، and sandy loam. The cumulative infiltration rates estimated from the different models were compared using eight different statistics. The results showed that the Kostiakov and NRCS models had the highest priority score and the most permanent trend for accurate estimating of cumulative infiltration rate in different land uses whereas the Horton model was situated in the next position. Overall، the empirical models (Kostiakov، NRCS and Horton models) had the more realistic efficiency than the physical models (Green-Ampt and Philip models).

The present research aimed to compare different methods of statistical analysis and to select the best method for achievement to the model among components of synthetic unit hydrograph by using of the physical characteristics of catchments, in northern catchments of Iran, with the area of 177000 km2 in Giulan, Mazandaran and Golestan Provinces. For execution of the research, 9 physical characteristics of catchment and 8 characteristics of unit hydrograph components for 44 storms in the north parts of Iran have been chosen. Regression test by using bivariate approach and various forms such as linear, logarithmic, inverse, quadratic, cubic, exponential, power and combined forms has been used after execution of factorial analysis. The obtained models were evaluated by relative errors, RMSE and efficiency coefficient. Results showed that the bivariate models have more accuracy in estimation of the amounts especially in the case of temporal variables (base time, time to peak, time to depletion). Regression of several variables has high accuracy in estimation of discharge and recursion regression of several variables has the highest accuracy.

Study of effective factors on morphometric characteristics of bed sediments may lead to better understanding of sediment transportation and deposition processes and finally, their efficient control or optimal utilization. The present study was aimed to evaluate the effects of erosion sensitivity of formations, land use and sand and gravel mining on morphometric characteristics of bed sediments at a 30 km reach of Vazrood River in Mazandaran Province, Iran. To achieve the study purposes, 9 sampling sections were selected so that the desired effects could be assessed. The bed sediments were then sampled using combining technique and the morphometric characteristics viz. mean, sorting, skewness, kurtosis, d10, d50,, d90, texture, sphericity and roundness were determined using sieving and GRADISTAT software. The results of the study revealed that erosion sensitivity of the formations, residential use and sand and gravel mining in the river all affected the natural trends of the sediments size parameters (mean, d10, d50 and d90 and sediment texture) as well as roundness, and reversed the trend in some sections.

Soil erosion and sediment yield from watersheds restrict sustainable use of land resources. Evaluation of governing process is، therefore، necessary for better understanding of the watershed system leading to appropriate management approaches. On the other hand، different behaviors of soil erosion and sediment yield as well as the necessity of regional studies have been often emphasized. The purpose of this study was to evaluate the applicability of rainfall and runoff variables of 8 storm events occurred during 2008 in prediction of storm-wise sediment yield in Educational and Research Watershed of Tarbiat Modares University (Kojour) with about 500 Km2 in Mazandaran Province. Both bivariate and multivariate regression models were applied with using simple and transformed dependent and independent variables. Results showed that the developed regression models had good capability for estimation of storm-wise sediment yield with coefficient of determination، above 0. 76، estimation error below 69% and efficiency coefficient of greater than 0. 52. These findings may be convincing for the application of the developed models in this investigation to other ereas similar to the studied area and laeaing to suitable soil and water management.

Quantitative investigation of effects of range management treatments on different soil and water components in rangeland ecosystems has been rarely taken into account. In the present research, the Kodir Summer Rangeland in the Southeast Nowshahr in Mazandaran Province was selected for studying effects of open grazing and exclosure managements on infiltration, runoff and microrelief. Experimental plots in dimension of 0.5×0.5 meters were applied in order to estimate runoff and subjected to rainfall intensity of 1.6 mm.min-1. The infiltration rate was calculated for each plot as the difference between the applied rainfall to and the runoff collected from each plot. The microrelief was also measured by using a wooden ruler graded in 10 cm steps and adjustable to the plot edges. The results were then compared on storm basis with the help of Tukey test. The results showed that there was a significant difference in infiltration, runoff and microrelief in two study treatments at the confidence level beyond 95%. The amount of total infiltration, runoff and microrelief in open grazing treatment were almost 0.97, 1.48 and 1.50 times to those recorded for short time exclosure treatment, respectively.

The Clark method is one of the most applicable techniques for development of instantaneous unit hydrograph whose efficacy depends upon the accuracy in estimating storage coefficient. The present study was conducted in Kasilian watershed in Mazandaran Province to determine the efficiency of developed hydrograph using Clark's method and to compare the Muskingum storage coefficients obtained through graphical, Clark, Linsley, Mitchell, Johnstone-Cross and Eaton methods. To this aim, the time-area histogram of the study watershed was initially developed. The 3h-unit hydrograph was then derived using the data collected in Sangedeh climatological and Valikbon hydrometric stations. The efficiency of Clark’s instantaneous unit hydrograph developed based on 6 methods for calculation of Muskingum storage coefficient was ultimately compared with the observed average 3h-unit hydrograph of the study area. The results of the study revealed that the Clark’s instantaneous unit hydrograph obtained from graphical method for estimation of storage coefficient with estimation error of less than 33.33% and efficiency coefficient of 83% could suitably simulate different components of the observed average unit hydrograph for the study watershed.

The present study aimed to analyze the comprehensive relationships between suspended sediment yield, and rainfall and runoff characteristics on storm basis in Khamsan Representative Watershed with an area of 4193 ha in Kurdistan Province, Iran. In due course, 9 storm events occurred during study period were analyzed 4 of which generated runoff and consequently yielded sediment. Different bivariate regression models were then applied for estimating sediment yield. The results of the analysis verified better performance of linear regression developed based on maximum rainfall intensity with respective determination and efficiency coefficients, and estimation error of 0.843, 0.84 and 39%.

Nowadays, measuring water quality is very important for comprehensive management of water resources. Suspended sediment is one of the most important water quality factors which greatly affects environment health. However, its measurement needs too much time and money. It was therefore tried in the present study to assess the applicability of modelling relationship between suspended sediment concentration and some easily accessible and cheap water quality factors. Towards this attempt, 61 water samples were taken during October 2007 to July 2008 from main outlet of Tarbiat Modares University Forest Watershed as a representative condition governing northern Iranian forest areas. The samples were taken during different hydrological conditions and corresponding lab analyses were consequently made. The results of regression modeling ultimately proved the relationship between suspended sediment concentration and turbidity, alkalinity, and phosphate with correlation coefficient beyond 0.264 (p=0.006), 0.088 (p=0.018), 0.987 (p=0.001) and respective estimation and verification errors of less than 78% in all classified periods, base flow, and flood conditions, respectively. The models obtained during the study can be then used for estimation of suspended sediment concentration in different hydrological situations.

Flood Damage is one of the most important problems in many countries. There are different methods for flood controlling by using indentification of flooding areas. Because most of the watersheds have different flooding seasons, the present study is going to comparison of temporal prioritizing of flooding of Kooshkabad sub-watersheds in Razavi province using HEC-HMS model. In this study we used of SCS hydrologic simulation method at Rainfall-Runoff transformation on sub-watersheds area, and Muskingum routing method on main channels for abtain of watershed outlet flood hydrograph after determination of data for flood hydrograph. Than we calculated prioritization of sub-watersheds to point of flooding conception using HEC-HMS model and we calibrated it on initial adsorption and curve number and lag time parameters in springal and Summer-Autumnal hydrologic priods. Than we prioritized particitation amount of sub-watersheds on peak flood discharge and flood volume in every hydrologic period, using one to one delet of sub-watersheds in flood routing. Paired samples t-test have used for indication of significant difference to point of statistical in temporal prioritizing of sub-watersheds flooding.The results of this research show that participitation amount of sub-watersheds on outlet peak flood discharge and flood volume in different periods is significant.

Water has a vital role in increasing crop yield in dry farming lands in semi-arid regions. This study was conducted to determine factors affecting runoff and develop an equation for predicting the runoff in the dry farming lands. The study was conducted in the Hashtroud, located in south part of East-Azarbijan province in northwestern Iran, from March 2005 to March 2006. A square network of dry farming lands with 900 km2 area was selected and divided into 36 regular grids with a dimension of 5 km. In each grid, runoff plots with dimensions of 22.1 m in length and 1.83 m in width at three replicates and 1.2 m spacing were prepared on a dry farming land with a slope 9%. At the lower parts of the plots, runoff-collecting equipments were established. Rainfall properties were determined on the basis of recording rain gauge data of a meteorological station. Based on results the runoff in the plots was affected by 23 natural rainfall events during the study period. The soils of the study area are mainly clay loam with a moderate infiltration rate and having almost 1% organic materials and 13% lime. Runoff amount per rainfall event varied frame 2.153 to 49.377 liter per plot. Runoff negatively correlated (r= -0.85, p<0.001) with soil infiltration. The results indicated that the runoff can be easily predicted using a linear regression equation based on coarse sand, organic matter and lime (R= -0.84, p<0.001). Coarse sand, organic matter and lime significantly increased soil infiltration and consequently reduced runoff.

Improper management of watershed land utilization has many ill effects on the available resources. Land use optimization is one of the proper strategies to achieve sustainable development and to reduce resource dissipation. Focusing on Brimvand watershed in Kermanshah province which comprises an area of 9572 ha, the present study was conducted to find out the most suitable land allocation to different land uses viz. garden, irrigated farming, dry farming and rangeland to achieve soil erosion minimization and benefit maximization. The soil erosion, net benefit and standard land capability maps were supposed as the inputs of the objective functions and to defined constraints. The multi-objective linear problem was then solved using simplex method with the help of ADBASE software package and ultimately the optimal solution was gained. Additionally, the results of the study revealed that the amount of soil erosion could reduce by 7.78% whereas the benefit increases at the rate of 118.62%, in case of implementation of optimal solution. The above mentioned optimization led to dry farming decrease and garden increase over that area. The results of sensitivity analysis also showed that objective functions were strongly susceptible to the variation of maximum constraint of irrigated farming and garden areas.

Insufficient information regarding the distribution of sediment yield during a storm is one of the old problems in soil and water conservation projects. Dotill now, the relationship between sediment and water discharge has only been investigated using the power equations and the position of samples have not been taken into account. In this paper, the concept of regression model was implemented to find out two separate equations defining the relationships between sediment yield and water discharge in two important segments of hydrograph namely, rising and falling limbs. The results revealed that the application of regression model is a suitable technique for the watershed is of Amameh and zamn Derakht in the study area.