نشریه مرتع و آبخیزداری
سال شصت و دوم شماره 1 (بهار 1388)

With respect to wide distribution of A. sieberi Besser in Iran, various studies have been done on its habitats and different ecological properties have been referred as effective factors in establishment of this species. In this research, we tried to study the ecological range of A. sieberi and its relationship with vegetative characteristics. Therefore, climate properties including annual precipitation, number of days with precipitation, annual, minimum and maximum temperature, absolute minimum and maximum temperature; topographic property including altitude; edaphic properties including pH, EC, SP, texture, lime, gypsum, C, Na, K, Ca, Mg, N and P; and vegetative characteristics including large and small diameter of canopy, height of plant and diameter of most thickness branch were measured in 34 populations. For determination of ecological range, normal curve with histogram of frequency have been drawed for total properties. All populations divided in 3 groups by cluster analysis. Measured properties compared by analysis of variance between 3 groups. The significant properties were: average of annual, minimum and maximum temperature, absolute minimum and maximum temperature, large and small diameter of canopy and height of plant in 0.1 % probability level, altitude and C in 1 % probability level, while annual precipitation, number of days with precipitation, N, P and Na in 5 % probability level.

The use of GIS tools is one of the newest methods for performance of different land evaluation and planning projects. This research with the purpose of determination of appropriate landuse to natural land potential and improvement of land management of catchments was executed using GIS-tools in Taleghan area. At first ecological and socio-economic resources determined, mapped and entered to GIS environment. Then by analysis of more than 15 information layers, homogeneous and ecological units determined. By the use of watershed management and combined land planning model and in accordance with natural and socio-economic characteristics of the watershed, suitable landuses were proposed. At last optimum landuse map and the existing state of landuse map were adapted in GIS space. The results showed that 17 percent of the watershed area has suitable landuses while 83 percent of the watershed area needs landuse change.

The aim of this research was to determine the effects of Camphorosma monspeliaca species on soil nutrient elements in its habitat. For rangeland, ecological positive or negative effects of plant species on environment must carefully be examined before allowing their plantation in vast areas; on the other hand this species with their special characteristics have special effects on their surrounding environment that should be considered. Camphorosma monspeliaca is one of non-native and adapted species in Chaharmahal and Bakhtiari province that its habitat has 3500 ha area. Effect of this species on environment requires more studies on their different aspects. Here we studied effect of this species on soil in order to assess its ecological effects on environment. This species distributed in all of the landscape but most distribution of species located at southern and northern aspects and in areas with flat topography. Companion species in topography position are different. This species can establish in non saline soil. The research was carried out at three stages of field sampling, soil test and statistical analysis. The research method was based on comparison between adjacent stand and stands of this species. Soil variables in two depth 0-10 cm and 10-30 cm were measured. Result showed that in two depths, were not significant difference but, in case of soil mineral elements, plant stands have significant difference; effect of depth and plant stands was not significant. There was significant difference adjacent stand and stands of this species in terms of Na, Mg, OC and in stands of this species were greater than the adjacent stands. This species increased content of carbon organic¬ and Na, Mg. From the results obtained on three topographic position, despite of negative effect of Camphorosma monspeliaca on sub soil with increase of Na and Mg, it can be concluded that Camphorosma monspeliaca had a positive effect on soil organic¬ matter. In general this plant has a good perspective and further studies about different aspects of this species are necessary.

The main structure of this study includes; isotopic tracer evaluation and measuring, to identify and origin of groundwater recharge, contributions determine of diffused recharge (DR) and concentrated recharge (CR) as well as determine drought and wet periods in Hashtgerd plain. The hydrochemical study which involved collection and analysis of water samples from the deep and dug wells, springs, tap water and rainwater showed that the rainwater is little source of groundwater recharge. The isotopical study aimed to determine the origin of the groundwater bodies and to offer support for the hydrochemical analysis. To achieve this purpose samples analyzed for H2 and O18 and data was quoted from literature about the isotopic composition of precipitation. The study shows that the isotopic composition during the rainy season ranges for ?O18 between -6/05 ‰ and -6/92 ‰ and for ?H2 between-45/92 ‰ and -52/27 ‰. The changes in ?O18 are correlated with those of ?H2 with R2 =0.9 that was similar to GMWL line. proving their meteoric origin. Cluster analysis supported by the Hierarchical Cluster Analyze, Chebychev and Mann-Whitney tests classified the analyzed rivers water samples into two main groups: the first cluster was included Kordan, Aqasht, Sorheh and Khor rivers. Because of the low runoff and high infiltration these rivers are recharged through groundwater. The second cluster was consisted Valian, Fashand and Hiv-shalamzar rivers. Because of the low infiltration these rivers are recharged through runoff. Cluster Analysis shows that the samples of groundwater of Hashtgerd plain were divided into three clusters. The first cluster was included west and north-east of Hashtgerd plain (Nazarabad, Hashtgerd town, Baraghan and Kordan) were recharged through surface water and rainfall. The second cluster was included north and center of Hashtgerd plain were recharged through surface and groundwater. The third cluster was included south-west and south-east of Hashtgerd plain which were recharged through groundwater. The results show that concentrated recharge (CR) supply groundwater more than diffused recharge (CR). Concentrated recharge was performed by watersheds and flood spreading. Using isotopic method, mean values of ? O18 and ? H2 in a mass-balance equation, the relative contributions of diffused recharge (DR) and concentrated recharge (CR), to groundwater were estimated to be 78 ÏÑÕÏ and 22 ÏÑÕÏ, respectively. According to results of this study, groundwater resource level decrease and there is a drought period in Hashtgerd plain.

Rainfall-runoff is one of complex hydrological processes that is affected by a variety of physical and hydrological factors. In this study statistical method ARMAX model, neural network, neuro-fuzzy (ANFIS subtractive clustering and grid partition) and two hybrid models of this methods were used to simulate rainfall-runoff and prediction of streamflow. In each method optimum structure was determined then, streamflow forecasted using the best model. The results showed that hybrid methods have better application than single models and artificial intelligent has better application than linear ARMAX model due to nonlinearity of rainfall-runoff process. In this study all methods showed relatively suitable application but ANFIS method with subtractive clustering is suggested for modeling rainfall-runoff and streamflow prediction.

Muskingum-Cunge is one of the widely employed methods for flood routing. Direct calibration of the model based on previous flood events is not required and the routing parameters in this method are determined according to physical characteristics and hydraulic conditions of the stream. During the last decade, different modifications were proposed for the method to increase its accuracy. In this paper Muskingum-Cunge method and its different modifications have been presented and the applicability and the precision of the proposed schemes were determined. To study the applicability of constant and variable parameter Muskingum-Cunge method in field conditions, some observed flood events of Karoon River have been routed with these methods. Inflow hydrographs were routed by the mentioned method and the results were compared with that of the observed values of the downstream end of the reach. The results were also compared with the outputs obtained by routing the same hydrographs by HEC-RAS hydrodynamic model. The results of this study demonstrated successful performance of the simplified routing methods and showed that in circumstances where the availability of intensive data required by hydrodynamic model are limited, relying on such simplified method would provide satisfactory results. Based on comparison among the results of the employed method with that of the hydrodynamic one, the most suitable method for the studied condition is determined.

In highland watersheds, runoff generated by snow melting plays an important role in stream water supply. SRM (Snowmelt Runoff Model) is a hydrologic model which simulates and predicts daily flow in mountain watersheds dominated by snow melting process. The SRM is based on the degree-day procedure which, is a widely used method but does not consider physical factors. In the current research, the factor of radiation was added to the degree-day model to develop a simple energy balance equation. Daily average radiation was calculated by albedo, shortwave and longwave radiation, daily maximum and minimum temperature and relative humidity. The snow covered area (SCA) was obtained from daily MODIS images. The developed model was applied to the stream flow data of Karaj Basin located in northern Iran and the results revealed that the coefficient of determination of the observed and estimated data was 0.677 while the differences between estimated and observed volume of runoff was -5.58%. Therefore, the radiation based of SRM increased the coefficient of determination of estimated and simulated discharge about 9.3%.

The research show that global climate changes and atmospheric general circulation are affected by large scale phenomena that occurred in the sea surface. These large scale phenomena are often named "climate large scale signals". These signals are calculated based on criteria such as sea Level Pressure (SLP), Sea Surface Temperature (SST) and so on. A method for weather forecasting is a special approach based on statistical modeling. In this study, data of 37 rainfall stations were used to model the relation between precipitation and Sea Level Pressure (SLP), Sea Surface Temperature (SST), Sea Level Pressure gradient (?SLP) and the difference between sea surface temperature and air temperature at 1000 HP. The results show that statistical modeling can successfully predict the amount of annual rainfall. The mean root square error for stepwise model were obtained 49 millimeters.

Study of soil and plant relationships is nessesery for ecological- based and appropriate management. The objective of this study is to determine the influence of edaphic properties on Haloxylon persicum growth and also, indentifing growth limiting soil properties for saxaul. The study was performed through the stratified random sampling and 3 sites were selected as follow: planted strong saxaul, planted weak saxaul, rangeland without saxaul. Then 6 samples of Haloxylon persiocum were selected in each region, meanwhile, plant parameters including canopy cover area, canopy cover perimeter, the smallest and the largest canopy cover diameter, average of canopy cover diameter, height, basal area and diameter were considered. Also, 9 profiles in sites were sampled and the followiong properties: pH, SP, EC, Ca, Cl-, CO3--,HCO3-, SO4--, gravel, CaCO3, CaSO4, organic matter, clay, silt, sand, available phosphorous, Na, K, CEC, SAR, ESP, PSS, PSW and TDS were measured. Ordination method was used for data analysis. Accordiong to the results, plant parameters have significant diffirences in saxaul sites with the same age. Soil physical characteristics including soil texture and chemical characteristics such as organic matter, available phosphorous, CEC, salinity, CaSO4 and CaCO3 content showed the highest influence on saxaul growth parameters.

The discharge of total suspended sediments (TSS) and dissolved nutrients from watersheds into receiving waters is a serious problem when natural vegetation is degraded by agriculture or overgrazing. This study was conducted in Soolegan Watershed to investigate land use change and overgrazing effects on phosphorus loss (dissolved & particulate), particle size associated loss of P and effect of time of rainfall on total dissolved P concentration in runoff. Much higher runoff, sediment and nutrient losses observed under cultivated land and HDP (high degraded pasture) than those under MDP (moderately degraded pasture). Contribution of particulate phosphorus exported from micro plot via surface runoff was increased by decreasing plant cover. Largest amount of dissolved phosphorus loss measured in HDP (16.4 mg/m2) and particulate P loss in cultivated land (301.3 mg/m2). Concentration of total dissolved phosphorus (TDP) in runoff was significantly (p

In this paper the utilization of GIS for the parameterization of rainfall- runoff process, physically based hydrological model components is described. The hytrogeneity of soil and vegetation in a catchment can be expressed with distribution functions of infiltration and soil storage capacities which derived efficiently by an overlay of a soil map with land use characteristics. These distribution functions are used to consider the non-linear distribution of actual saturation within a catchment with regard to their impacts on generation of excess rainfall and deep percolation during a storm event. The newly developed infiltration model components and its parametrization by GIS was successfully applied to Kechik catchment. To obtain the nesessory information a simple digital soil map of the catchment was constructed by discretizing the watershed into 1×1 km2 grid cells, and combined with the land use classification to estimate for each cell in a soil texture class the areal distribution function of infiltration model parameters consist of surface soil moisture content, maximum and minimum infiltration capacity rate (Sm, fo, fc), coefficients of model (K1, K2, K3 & K4) and excess rainfall. The results of the model application are shown that the rainfall-effective runoff relationships during storm events in catchment, by application of GIS technology, a new generation of hydrological model for micro and macro scale can be developed under consideration of catchment characteristics and their spatial heterogeneity.