دکتر مهین کله هویی

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.

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.

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.

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.

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.

Nowadays, organic mulches are used as protective cover for the soil surface.This study in order to investigate the effect of protective cover straw Colza on the components of start time and runoff coefficient in loam – sandy soil in laboratory scale and using a rain simulation with an intensity of 50 mm / h with a 10-minute duration has been done. For this purpose, three levels of protective cover of straw Colza one control treatment  with four levels of moisture, were considered in three replications. The results showed that the application of protective cover of straw Colza would increase and decrease respectively, start time and runoff coefficient. Increasing the level of protective coating in each of the moisture levels increased and decreased, the start time and the runoff coefficient, so that the treatment without protective coating with a moisture content of 30 percent had the lowest starting time and the maximum runoff coefficient with values equal to 28 seconds, and 19 percent and 75 percent of protective cover with dry air humidity had the highest starting time and the lowest runoff coefficient with values equal to 635 seconds and 4percent. Increasing the level of moisture reason increases the runoff coefficient and decreases its onset time, but by applying the protective cover of straw Colza its intensity has decreased. Organic mulch cause delay in occurrence and reduces the amount of runoff coefficient.

Drought is a serious danger with very extensive impacts on the soil, economy, and the threat to the livelihood and health of local communities. This disaster as an unpleasant climatic phenomenon that directly affects the communities through restrictions on access to water resources, causes high economic, social and environmental costs. Meteorological drought indicators are calculated directly from meteorological events such as precipitation, and in the absence of these data, drought monitoring will not be useful. Due to the fact that meteorological drought indicators are only valid for a single location and do not have the required spatial resolution and are also dependent on weather station information, and these stations are often distributed distantly, the reliability of these indicators has been questioned. Given the characteristics of satellite data such as spatial and temporal resolution, extensive coverage of studied areas, and direct investigation of vegetation status by satellite indices, many studies have been carried out for drought modeling using this technology and these indicators. Over the past four decades, far-reaching drought monitoring tools have been widely developed and drought monitoring models are widely proposed, which are generally based on vegetation indices, surface temperature, humidity and reflection in the visible and infrared regions. These include leaf water content index, vegetation cover index and temperature - drought - vegetation index. Therefore, remote sensing techniques can be a useful tool in drought monitoring. The purpose of this study is to monitor drought and vegetation health in the city of Kermanshah using LANDSAT satellite imagery. For this purpose, first, by examining the rain-gauging and synoptic data of existing stations and using the standard precipitation index model, the driest year and one wet year were selected as the sample. In this study, two years of 2015 and 2016 were selected as the dry and wet years and then, the vegetation cover of the region was compared with the Landsat images. To use these images, it is first necessary to make sure that there is no geometric error. For this purpose, the road vector layer was used, which was revealed that the images have geometric errors. Images with less than a half-pixel error were corrected geometrically using 21 and 24 auxiliary points. The adaptation of the vector layers with the roads existing in the image indicated the accuracy of the correction. At the next stage, the driest year and one wet year were selected as samples by examining the rain-gauging and synoptic data of the existing stations and by using the standardized model of rainfall index. At the next stage, the Temperature Condition Indices and Vegetation Health Index (VHI) were compared in two wet and drought periods were studied in order to determine the differences of these indices during a dry year and a year with high precipitation. For this purpose, each of the aforementioned indices was built using the LANDSAT-8 imagery, and the stages of building these indices were subsequently presented.  The required pre-processing and processing as well as the geometric and radiometric corrections were first performed on the satellite images. Then, temperature condition indices, vegetation status index and vegetation health index were prepared for drought monitoring. Considering that, the meteorological drought indices are only valid for a single location and lack the required spatial resolution and are also dependent on the information of the meteorological stations, and these stations are often distributed far apart from each other, the reliability of these indexes has been questioned. Satellite data characteristics like high spatial and temporal resolution, extensive coverage of the study areas, and direct survey of the vegetation status by the satellite indexes have led to a large number of studies on drought modeling using this technology, and the confirmation of the use of these indices. The aim of this study is to determine the moisture, heat and health of the vegetation using the LANDST images. Thus, the results of the study in the next stage indicated that the LANDSAT images and the built indices have the required capabilities to monitor drought. The results of this research can be a proper option for decision-makers to effectively supervise, examine and resolve the drought conditions and double the necessity of profile definition. Supplementary studies are suggested for spatial drought monitoring by satellite imagery through ground measurements of the quantitative changes in the coverage and temperature of the earth’s surface. There are limitations in the use of NDVI and satellite thermal bands. These include weather and cloud conditions that should be considered. Using maps obtained from the drought monitoring and evaluating indices can help improve drought management programs and play a significant role in reducing the effects of drought. Using vegetation health status index, it was determined that the vegetation status has had a lot of changes during drought compared to the wet period, hydrological drought has had a major share in the destruction of vegetation and drying of the lakes and, consequently, the abandonment of agricultural lands and the lack of access to alternative water resources, as well as the lack of groundwater resources or the lack of alternative surface water resources have intensified, and it seems that, this part of Iran will face numerous problems if the drought continues in the coming years and the appropriate methods are not used to deal with it. Also, given that the water resources of the region are going to decrease in the coming decades, the necessity of using comprehensive water management methods in all sectors, including the reserve, transfer and distribution sectors seems very essential and inevitable. Finally, it is expected that the trend of destruction of vegetation decreases in the future by applying proper management practices, sustainable water distribution, regional negotiations, methodical agriculture as well as the establishment of optimal hydrological conditions.

Drought is one of the phenomena that has recently been identified as a major challenge , and has incurred a lot of damage in different parts of the world. The purpose of this study was to investigate and map drought in Kermanshah Province using the CZI index in ArcGIS for 1995-2016 using data from synoptic stations of Kermanshah, Kangavar, Sahneh, Harsin, Mahidshah, Sararood, Paveh, Ravansar, Saripul Zahab and Islamabad  Gharb. The results of this research indicate that 50 percent of the province's surface area during the 22 year period has experienced drought, with the most severe drought for Mahidshat and Saripul Zahab stations in 1999 with an index of -2.25 and -2.12 respectively. The least severe drought was observed in 2013 with an index of -0.22 for the Sahneh station. Also, in 1997 the highest rainfall was recorded for the Sarpul-e-Zahab station  with an index of 2.18 and the lowest was recorded in 2009 and 2011 at Mahidshat  and Saripul Zahab stations with equal indices of 0.01. According to the zoning maps, the region has experience 11 drought periods and five wet periods of varying severity.

Soil erosion is a global problem that seriously threatens soil and water resources. This research was conducted to study the effect of protection of colza straw on runoff and sediment yield from the laboratory plots using the rainfall simulator. Three coverage of 25, 50 and 75% of colza straw mulches and a control treatment (without coverage) were considered with three moisture levels of 15, 20 and 30% in three replications. The results showed that colza straw had a significant effect on runoff and sediment reduction. All moisture levels in three protective coverage levels decreased runoff volume by13.14, 26.29 and 31.52%, respectively, and sediment yield by 41.21, 72.4 and 78.78%, respectively. With increasing of protection coverages from no cover to the higher coverages, the trend of runoff and sediment yield decreased, so that the lowest amount of runoff (1821 ml) and sediment yield (58 g) were measured in the protective coverage of 75% with the moisture of 15%. The highest amount of runoff (5501 ml) and sediment yield (522 g) were observed in the control treatment at a moisture level of 30%. With increasing the moisture levels from the amount of runoff and sediment yield increased. Moreover, by applying the protective cover, runoff and sediment yield decreased at the same moisture levels.

Drought is one of the atmospheric phenomena that adverse effects on various sectors environmental, economic and social gradually identified and is tangible and that is the reason it is also called creeping disaster. In this study, droughts zoning for five years consecutive caspian plain with using spi and czi indices with Arc Gis for stations synoptic: Astara, Inchebron, Bandar anzali, Babolsar, Ramsar, Rasht, Ghaemshar, Gafarhaji, Gorgan and Noushar collected. For this purpose, total rainfall for 25 years 1986 to 2010 was considered .The results indexs show that, most wet year for stations Astara with index respectively 2.6 and 2.22 in 2000 year and most dry year for station Babolsar in 2010 year with index respectively -2.86 and -2.39. Based maps drought five year in 1990 most of the drought in the eastern part of the caspian plains and other areas faced with lower rates. in 1995 year the drougt has led to the central plain and in 2000 year area west and central plains experienced drought magnitude is different. in 2005 year drought with differeant magnitude occurred in all parts of the plains and also in 2010 year all part plain caspian withness drought and process drought has decrease in east to west plain caspin.

Imbalance soil erosion is one of the dangers that threatens the availability of natural resources to communities by the high amount of runoff and sediment production. To control the effect of soil erosion, the application of the governing principles on the use of organic and inorganic soil stabilizers can be considered as an effective manner. The purpose of this study was to investigate the effect of different amounts of Colza straw on runoff and sediment of loamy-sandy soils in the laboratory conditions. For this purpose, rainfall of 50 mm h-1 with duration of 10 min on plots with scale of 0.5 m2 in the three replications, with coverage values of 25 and 50% protection of Colza straw from industrial fields of Dasht-e- Naz Sari City is harvested and was simulated using rainfall simulator of Faculty of Natural Resources, University of Agricultural Sciences and Natural Resources of Sari. The coverage values of 25 and 50 % of Colza straw provided from industrial fields of Dasht-e- Naz, Sari city was used for the present study. The results showed that the application of both levels of Colza straw had a significant effect (p