نشریه مرتع و آبخیزداری
سال شصت و هشتم شماره 2 (تابستان 1394)

Owing to the oncoming needs and increasing the population of Lake Urmia Watershed، providing equilibrium between water supply and demand seems quite challenging and the Lake cannot be successful in meeting its ecological demands in this critical condition. In this unfavorable situation، water resources must be managed through a sustainable context. With this knowledge in hand، a multi attributes framework was applied to investigate the preference of supply or conservation alternatives. Preference of sustainable development attributes was calculated in a pairwise hierarchical structure and instead of time-consuming conventional procedure، Absolute Measurement was used that compares qualitative scales instead of alternatives and can overcome the problem of rank reversal in pairwise comparison. Ranks of the Alternatives were evaluated by VIKOR method which can provide a set of compromise solutions instead of one solution. Due to sensitivity analysis performance، VIKOR was introduced as a robust model in ranking the water resources alternatives. With regards to the results of this two-stage hierarchical-compromising approach، dealing with Watershed crisis is depended on organized indigenous collaboration، water use optimization and protecting available natural resources. On the other hand، supplying water by structural development without sustainability consideration would not be effective.

Because of insufficient factors including facilities، budget، human resources as well as time watershed operation is not applicable throughout the basin. As a result، watershed operation should be performed in the sub-basins in which is more affectionate and the risk frequency of some events such as destruction، degradation; physical and financial damage and also flooding are considerably high. In addition، due to hydrometric stations، defects or the lack of stations in some areas، some efforts have been made experts recently to assess and consequently introduce some novel and reliable methods for prioritizing on the basis of current data obtained from sub-basins features of different geographical regions. In current study، the utilization possibilities of neuro-fuzzy technique and SCS in HEC-HMS model that have different potential to examine a wide range of advantageous and disadvantageous in making various decisions were studied. To determine the prediction accuracy of these methods، the rate of flow and sediment output of Taleghan sub-basins were taken over one year. The results of these methods were then compared with the maximum two-year return period flow observations. Our results revealed that in making prioritization، neuro-fuzzy as compared with the SCS method can produce the best prediction as long as the coefficients of errors، efficiency compared to the observational data and predictions are taken into account.

The purpose of this research is investigation of relationship between vegetation cover and soil characteristics and determination of the most important soil factor that effects on quantity variations and kinds of vegetation cover in the study area. The study area is located in west of Tehran province and south eastern of Hashtgerd، next to Najm-abad village. After field study، the index vegetation types were selected and randomized-systematic sampling method has been used for soil and vegetation cover sampling in each of key area. The area of each plot was determined according to kind of plant species and species distribution using minimum area method. Some vegetation cover parameters such as canopy cover percentage، density and frequency of plant species were measured in the area. Then soil sampling were done from 2 horizon 0-10 cm and 10-30 cm in each plot and soil attributes such as texture، pH، organic carbon percentage and gypsum were measured in soil laboratory. Afterwards statistical methods like multivariate regression، analysis of variance and statistical techniques were used for analyzing of soil and vegetation cover data. Results showed that there is not any specific difference between soil and vegetation data except for gypsum. In other words the effective factor on vegetation cover variation was soil gypsum.

To assessment and preparation of desertification mapping، much research has been conducted ever within and outside the country that has led to numerous regional models. To provide a regional model and quantitative assessment of current state of desertification، ShahrBabak plain with an area of 4112 square kilometers (Km2) located in the Northwest of Kerman province were considered. In this study، to assess the severity of desertification using thirteen indices that five of them based on groundwater and include: electrical conductivity (EC)، sodium absorption ratio (SAR)، chloride (Cl)، drop of groundwater and water table depth and three of them based on climate data and included: annual rainfall، Transeau drought index، drought index and also three of them based on vegetation and included: Conditions، exploitation and restoration of vegetation، water erosion and irrigation methods in format of desertification Iranian model IMDPA to investigation and determine the class of desertification intensity were done in each of work units. The final score of each of work units and then total area were determined using Geometric average from any of the mentioned indices. Finally the current status of desertification intensity classes were estimated in low، medium، high and very high classes. The results indicated that in the regional proposed model، the study area with respect to intensity of desertification is placed in about 61351 ha (14. 92 %) in low class and about 138575 ha (33. 7%) in medium class، about 117685 ha (28. 62 %) in high class and about 93589 ha (22. 76 %) in very high class. Also the weight average of quantitative value estimated 2. 06 in total area that it indicated the medium desertification class in the total area.

The present study was conducted in the rangeland of Glandrood watershed in the province of Mazandaran. The objective of this study was to compare between the ecological amplitude of Festuca ovina L.، and Poa bulbosa L.، using the function HOF along the gradient of the environmental variables. For this purpose 150 plots of 1m2 were established along the altitude gradient. The sampling method was randomized-systematic. In the area sampled، frequency of Festuca ovina and Poa bulbosa، altitude and slope were recorded. Soil samples were taken from 0-20 cm in each plot. In each sample، bulk density، pH، N، EC، organic matter، organic carbon، the percentage of sand، silt and clay were measured. In order to study the shape of response curve and the ecological optimum in relation to the mentioned variables، HOF function was used with binomial distribution function. The data were analyzed by R ver. 3. 0. 2 software. The two species Festuca ovina and Poa bulbosa، mainly showed different ecological amplitude along the gradient environmental variables. The results showed that the ecological amplitude and optimum alonge altitude gradient for Festuca ovina has been recorded 2244-3037m and 3037m respectively for Poa bulbosa 2335-3037m and 2636 m respectively. Also the response curve of Poa bulbosato the altitude has unimodal and symmetric but for Festuca ovina was monotonically increasing trend. The response curve ofPoa bulbosato pH is monotonically decreasing but for Festuca ovina was unimodals symmetric.

Water resources local governance can is one of the most influential collaborative approach in the water resources management. Social monitoring of local stakeholders plays an important role in planning، resources management and water efficient governance. Therefore to achieve this goal، social network analysis has been considered as an approach of analysis of the relationship among local stakeholders، in order to sustainable management of water resources. This study aims to social monitoring in local stakeholders network using social network analysis in Razin watershed located in Kermanshah province. This work based on social network analysis approach as method with emphasis on trust and collaboration ties and quantitative and mathematical indicators on the macro-level of local stakeholders network (Density، Centralization، Reciprocity and Geodesic Distances). The results showed that the level of social capital in the village has been measured weak. The degree of reciprocity indicator for trust and collaboration ties and the stability of network is weak. Also the level of correlation between trust and collaboration is 37 percent. The results of the mean geodesic distance on the basis of trust and collaboration ties showed that circulation velocity of trust and collaboration is moderate to low. Can be concluded on the basis of the results، weak social capital and low union between stakeholders، makes reduce circulation of trust and collaboration and therefore local governance of water resources in the region is challenged

Check dams، are small dams in the watershed. These dams are constructed in susceptible areas to erosion due to reduce of flow velocity and erosion، control of sediment and flood in upstream of reservoir dams. These structures are made using wood، stone and cement، and Gabion. These structures change the hydrological response of the watershed by reducing flow velocity، the channel slope and storage of flow. Analyzed the effects of these dams before making can be deciding on the correct and efficient implementation of the project as well as better management in order to achieve various objectives effectively. Since the constructions of these dams are effective on flood behavior، this research aims to impact of check dams on time of concentration and reduction of flood peak discharge in the Gash watershed. In this research are used from Puls method for flood routing in reservoir and Muskingum method for flood routing in river due to evaluate the impact of dams، and also flood hydrograph with 25 to 100 year return period was simulated the situation before and after construction of dams. The results showed that the proposed check dams are reduced peak of flow between 75 to 97 percent and flood volume from 73 to 98 percent that shows the positive effects of the construction of these dams in reducing the peak of flow and flood volume. In addition، in different return period with increasing peak of flow and flood volume، reservoir role in reducing peak of flood discharge and flood volume will be decreased. Also time of concentration will be increased between 0. 26 to 0. 98 hours by Construction of check dams.

The behavior of suspended sediment during flood events is not only a function of energy conditions، i. e. sediment is stored at low flow and transported under high flow conditions، but also is related to the variations in sediment supply and sediment depletion. These changes in sediment availability result in so-called hysteresis effects. Therefore، Hysteresis pattern analysis is of great importance in sediment studies in the watersheds. However، their analyses has been rarely considered. In this study، based on the discharge and sediment concentration data collected from 8 storm events occurred during March 2 011 to April 2012، event suspended sediment dynamics of 7 tributaries of the Lake Zarivar watershed was investigated using hysteresis patterns. Based on the fact that all sampling points were not active in all events، about 46 hysteresis patterns were obtained. The analysis of results showed that 16، 13، 11، and 6 events had clockwise، irregular، complex and counterclockwise patterns، respectively. Small tributaries of the Zarivar lake watershed showed the rapid responses to the variation of storm intensity and the most hydrographs of different storms were multi peak discharges and consequently high suspended sediment variations led to different hysteresis patterns. The diversity of patterns suggested that the detailed processes of sediment transport were not only complicated during one event but also varied from event to event. The reasonable and statistically significant relationship (p<0. 05) between suspended sediment yield and peak discharge of each sampling point indicated that the data from all events may be statistically well described by a simple regression equation، regardless of different inter and intra-storm variations of the suspended sediment.

To evaluate the vegetative and productive characteristics and forage utilization by livestock at different stages of Bromus tomentellus Boiss. Phonology، this experiment was carried out during five years in Kordan Rangeland of Alborz province rangelands. So starting the grazing season and livestock entering، any remaining amount of forage grazing was harvested until a month intervals، and utilization rate was determined by subtraction between harvested forage and fenced plot forage. Finally، in order to study the effect of harvest months on the production and utilization of specie under investigation in the study area، data were analyzed. In overall، the results of this study were showed that highest production was belong to third and fourth years and least production was belong to first year. The utilization changes were similar to production changes. In addition، growth and production period Bromus tomentellus Boiss. was spring. The growth and production this plant was maximum in April and then reduced in July. The forage of this plant in May and June has been strongly grazing in the study area. In July the utilization rate this plant was decreased. It seems that the complete growth stages، this species have a woody and livestock grazing has less on it. Thus reduce the amount consumed by livestock.

Considering the importance of vegetation changes and awareness of its destruction or improvement trends in programming and its proper managing of utilization، this study was conducted in order to survey the effects of grazing on the qualitative and quantitative components of vegetation (including life form، growth form، palatability class، plant families and species diversity) and recognition their most important changes in both grazing and enclosed sites in Kalpush plain، Golestan provience. For this purpose، samples were taken via 78 plot 1 square meter in a randomly- systematic method. Mean comparison of the components and recognition of the most changeable components in consequent implementing grazing management were done with t-student test and principle component analysis (PCA) respectively using Spss software. According to the vegetation study، 13 species belong to Asteraceae family and 10 species to Poaceae family and there are 69 Herbaceous species، 13 Grass species and 5 shrubs species of plants in this region. The results of t-Student test indicate an increase in relative density of Therophytes and class I plants، and decrease in Cryptophytes and class III in the enclosed. Also the results point out that grazing has caused increasing in the relative canopy of Shrubs and Champhyte and decreasing in Therophytes، Forbs in the region. Comparison of relative density and canopy cover of plant species in two sites showed a relatively good effect of rangeland enclosing in increasing of the density، restoration and recovery of species composition and diversity. Principal component analysis also showed that the most changeable components in consequent of rangeland enclosing were Forbs، Hemicryphtophyte، Therophyte، Appiacea and Brassicacea families in positive and Shrubs in negative of first axis. Also the Papaveracea and Asteracea families have the most incremental changes in the second component.

Estimation of evapo-transpiration is necessary in cases such as irrigation planning، determining of evaporation of the water bodies، water balance assessment، estimation of runoff and watershed management and ecological and meteorological studies. Evapo-transpiration can be determined precisely using field measurements. However، these methods provide evapo-transpiration just for limited areas from spatial point of view. This limitation has motivated the development of using remote sensing data to evaluate evapo-transpiration over vast area. Surface Energy Balance Algorithm for Land (SEBAL) is a new model that has been used at different areas all over the world for estimating of evapotranspiration. Due to the fact that no written report in evapo-transpiration estimation using this algorithm in the country has been published yet، the objective of this study is to investigate the validation of revised SEBAL model in mountainous region. In this project، actual evapo-transpiration values were estimated using MODIS image data and revised SEBAL model for mountainous region in 22 different dates in 2006 in Taleghan Drainage Basin. The result showed that the correlation between estimated and measured values is significant (R2=0. 88، p<0. 001). Thus، MODIS image data and revised SEBAL model were able to estimate actual daily evapo-transpiration values in Taleghan Drainage Basin. Therefore this revised algorithm could recommend as suitable method for further studies in different area with variation topography.

Loess Deposit is one of the most important Quaternary Deposits of northeastern parts of Iran which have high erosion rate. This study was performed with field- Rainfall- Simulator which has a plot area of 1 m2 in Gorganrood Drainage Basin to determine the effective factors on sediment yield. Landuse، slope and erosion feature maps were overlaid in GIS to obtain land unit map. Then on work units، rainfall simulator analyses were performed. The produced runoff and sediment in 69 points on work units were collected and were measured. Adjacent to each rainfall simulator plot، samples of surface material were collected in the field to analyze for physical and chemical characteristics. In the field، descriptive tables were prepared for different work units in which locality، slope percentage، elevation، depth of A horizon of the soil and other necessary informations were recorded. In order to determine logical relationship between different variables، regression and correlation analyses were performed. In statistical analyses، it was found that slope percentage has the highest correlation coefficient and has the highest direct relationship with sediment yield and sediment production and silt amount is the second factor. The investigation of multiple regression analyses generated a model which shows %80 of sediment production variations. In this model slope percentage، cation exchange capacity and silt have possitive relationship and Calcium cation has negetive relationship with sediment yield.

Suspended sediment estimation is an important factor from different aspects including، farming، soil conservation، dams، aquatic life، as well as various aspects of the research. There are different methods for suspended sediment estimation. This study aims to estimate suspended sediment using feed forward neural network with error back propagation with Levenberg-Marquardt back propagation algorithm and compare the results with best sediment rating curves among commonly used sediment rating curves، including: linear، seasonal، monthly and Mean load within discharge classes. To attain this، the sediment discharge and the corresponding water discharge data for ten hydrometric stations of Lorestan province of Iran were used. In next step different methods of sediment rating curves along with different correction factors، a total of 20 methods were applied to data. Results showed among examined methods; monthly rating curve with MUVE correction factor has been selected as best، based on Nash and Sutcliffe index and accuracy index. Then results of estimating sediment load by using selected sediment rating curve were compared with the results of the neural network. Mean-square error and Nash and Sutcliffe index were applied to select more appropriate method. The results showed the suitability of the feed forward neural network error propagation in compare with sediment rating curves.