نشریه پژوهش های آبخیزداری
پیاپی 107 (تابستان 1394)

Applications of rainfall-runoff models, are to determine the hydrologic behavior of watershed and to simulate the flow, for designing hydraulic structures and specially evaluating the impacts of operations on the flow regime. According to deficiency of hydrometer data in most of Iran’s watersheds, using simple and convenient hydrologic models and developing them for watersheds without stations is essential. In this context, several methods have been proposed. This study has been compared the consistency, accuracy and reliability of geomorphologic, geomorphoclimatic and nash instantaneous unit hydrographs, in estimating outlet runoff hydrograph characteristics, in Manshad watershed. For this purpose, six storm events were chosen, by using the area’s hydro-meteorological data. Then, the methods’ needing parameters, including the area’s morphometric characteristics and the events properties, were calculated. Thus, outlet runoff hydrographs, for each method were determined. Evaluations that have been carried out by using the mean relative error, the root mean square error and the Nash-Sutcliffe indices, confirmed the higher efficiency of Nash model, in estimating peak discharge, with an error of 23.75, time to peak with an error of 28.21 and the complete shape of hydrograph, with efficiency criterion of 0.4, than the other methods. In addition, this method has a high potential in simulating the actual amount of flood volume, with an error of 9.90. Thus, nash model, compared to other models (based on this study), is the most efficient model for estimating flood discharge.

Excavation and embankment machineries removes vegetation cover during construction of roads, which is resulted in accelerated erosion particularly in mountainous areas. This issue has received little attention in Iran so far. In this study, WARSEM model was used in order to quantify sediment production from 12 km road in Vard-Avarad’s upstream mountainous basin, Tehran providence. To achieve an accurate estimate in any study, collecting adequate data from all population (in this case the road) is prerequisite which resulting in an increase in both time and cost of the project. Survey sampling techniques can be used to reduce the time and cost by studying a few elements (selected road segments) of the population (whole length of the road). As the first step, each 100 meters of road segments was considered as a sampling unit followed by determining the sample size equal to 17 using Cochran equation. In the next step, the selected road segments were located on the road by systematic sampling design and all model factors such as road width, gradient, lithology, surface cover of both cutslope and fillslope were measured. Sediment production was then estimated in each road segment using WARSEM model. The results showed that total annual sediment yield originated from roads is about 3384 ton (989 and 2137 ton from cutslope and fillslope respectively) and specific average load is 157 ton/ha/yr. The findings demonstrate the importance of three factors including surface cover, height of slope, erodibility of geologic formations compared to the other factors. The validation of results was tested based on standard error of estimates, comparison to the volume of debris in the foot of cutslopes and the amount of sediment excavation conducted by Tehran Roads and Urban Development Organization. The relatively low standard error of estimations and the lower cost and time spent as well suggest the privileged performance of sampling design in estimating of sediment yield despite studying only about 14% of the road length. The remained differences between the observed and estimated sediment can be explained by considering the short period of observations compared to the long-term average of sediment yield calculated by the model.

Implementation of management policies and sediment control is considered requirements. And requires of these programs, identifying and obtaining information about the relative importance of sediment sources and there by identifies critical areas within the watershed. In this study, Sediment deposited in the behind of sediment control structures were studied that constructed on the main channel watershed Nokandeh in Golestan Province. The purpose of this studyis separation of sediment sources with using the tracing method. The first, accordingto available information and maps of the lithology was determined land use, erosion and slope map units and in every work unit were taken the number of three sediment samples.Then samples being analysis in laboratory with X-ray diffraction and 9 clay minerals recognized based on statistical methods Kruskal Walis and were evaluated of discriminate function. The results indicate the proper separation of sediment sources, so that 2 clay minerals the Muscovite and Quartz could have %100 separation sediment sources. Average of low relativeerror, the high performance coefficient above model and also good consistent results with field observations show that tracers method was utilized in this study, a method is valuable for the separation of sediment sources in the watershed. The reesults also showed that using a combination of tracers characteristics, sediment sources separation rates are significantly higher than any of the individual properties.

In Iran, with semi-arid climate conditions, optimum use of limited water resources has particular importance. Conducting research projects in area of water resources, especially in recent decades, due to encounter of human habitats to climate change and drought phenomena is essential. In this study the influence of climate factors on fluctuations of Parishan Lake water level during 1973-2009, was conducted using statistical models. Projection of climate factors for the next three decades also was done by the ARMA (1, 1) model using the SAMS software. Finally, by regression models projected parameters were used to simulate Parishan Lake water level for the next three decades and determining the best model. Findings suggest that the effective climate factors influencing Lake’s water level fluctuations consist of precipitation, evaporation and temperature. These findings reveal that Lake’s water level fluctuations are mostly governed by natural climate variations, hydrological cycle and drought return periods. These models showed that lake’s water level fluctuations exist in the future and the projected data predicted increase of lake’s water reservoir and water level for upcoming years.ý

Determination of preference value of plant species which grazed is an important factor in evaluating the appropriateness of rangeland with livestock. Desirability of forage plants for livestock and wild animals is This desirability in determination of range condition, range capacity and scientific management of rangelands is used. Thus attention to the preference value of plant species in a region is a key factor which can guarantee the success of management in achieving its goals. Therefore the preference value of plant species by timing method for sheep was determined in Polour in Mazandaran province. Method was this form That within 4 years and 3 months (July, August and September) and two times in one day each month and each time about 20 minutes from of grazing cattle was shot and then transfer film to Computer , Grazing time of plant species was determined. The results showed in 1% level There is significant differences Between different species in terms of duration and Percent of the time grazed. Also results showed average grouping Percent of the time grazing which threr are 4 groups . thr highest of present of the time grazing related to Elymus hispidus var hispidus and lowest of present of the time grazing related to Asperula odorata.

The aim of present study was performed for study of spatial variation of Artemisia aucheri yield, density and canopy cover and its spatial relationship with soil properties and topographical factors in Baladeh semi-steppe rangelands, Noor. For this reason, 132 sample points were carried out within the form of a network of 550 × 600 m with the systematic method by the plots in 50 m through transects. Soil samples were taken in depth of 0 to 20 cm and the samples elevation, latitude and longitude were registered by GPS device and the slope percent was measured using a slope meter. To determine the yield, density and canopy cover percentage of Artemisia aucheri was used plots of 4 m2. The data normality was determined using Kolmogorov–Smirnov test and correlation of data using Pearson correlation coefficient using SPSS software. To perform of geostatictics analyses and provide of spatial distribution map were used GS and Arc/GIS softwares. According to spatial correlation analysis, among soil properties and topographical factors, soil organic matter and clay showed, a more strong space structure with the study species, Interpolation and obtained maps for spatial distribution of Artemisia aucheri was performed using Kriging, Cokriging and inverse distance weighting methods. In this study, except density, yield and canopy cover of Artemisia aucheri showed a weak space structure using Kriging. This result shows that this method were not validated for spatial variability of yield and canopy cover of Artemisia aucheri but were obtained a strong space structure using Cokriging methods for studying variables.

Salinity stress limits forage productivity, and plays a major role in determining the distribution of plant species across different types of environments. Medicago polymorpha and Medicago scutelata are annual legumes species that product valuable forage and grazing material in pasture and rangelands of Iran. The objective of this study was to evaluate the effect of the salinity stress with Na 2 So4 on Forage quality of Medicago polymorpha and Medicago scutelata. The experimental design was completely randomized design with five levels of salinity stress 0, 50, 100, 150 and 250 mM with Na 2 So4 in four replications and 50 seeds per replication. Seeds were grown in plastic pots in sterile sand in greenhouse. All pots were irrigated with distilled water until germination stage. Then the pots were irrigated uniformly every other day with modified Hoagland’s nutrient solution during 40 days and finally forage quality was measured. The data were analyzed using SPSS software. The difference between the means was compared using Duncan test (P

Undoubtedly, soil conservation programs through the integrated management of watersheds, preventing erosion and maintaining an effective will be a valuable resource. In the Soil Universal Soil Loss Equation (USLE) ,soil erodibility is estimated by nomograph.The soil texture, field capacity moisture, organic carbon content and very fine sand content of each sample was determined. Soil erodibility is measured in different methods. Simulator is the simplest and easiest methods.
The results showed that there is a little correlation between K wischmeier and k simulator While the K simulator has a high correlation with k bisal. This methods measure the erosion rate in the first stage. Rain simulation system used for the application splash erosion. Splash erosion is recognaized as the first stage in the process of soil erosion. Basic processes in erosion disperse soil particles by rain drops and changes caused to the soil structure which are moved by runoff.

Studies of river engineering and River cross structures design such as bridges, diversion dams, Water Intake, etc. have closely related with the accurate calculation of depth, flow velocity and it has estimated moment of maximum flood discharge. The Estimated of flow velocity is important in hydraulic and hydrology studies .where no enough measured data is available, empirical approaches are usually applied to estimate flow velocity and maximum flood discharge. The most of these methods have been proposed for a certain area with specific physical and climatic conditions .to use these methods in other areas with different conditions ,evaluation and analysis of sensitivity of their parameters seems to be necessary. In this research ,new simple and efficient method is used to carry on sensitivity analysis of 2 flow velocity estimation methods including Manning and chezy that both of them are the most famous flow velocity existing. The results show chezy empirical equation is more sensitive Manning equation in estimating flow velocity. At the Manning equation, Model sensitivity is more to the less roughness values and when the energy line slope value (surface water) is high, flow velocity sensitive is increases. In other word, small changes in high slope, the flow velocity has changed dramatically. Sensitivity of Output’s model to hydraulic radius parameter is higher than while the area of catchment increases. Results show that roughness coefficient (c) in chezy equation is the most sensitive parameter and it need to more attention and correction.

Rainfall-runoff process is physical phenomena that their investigation is very difficult due to effectiveness of different parameters. Various methods have so far introduced to analyze these phenomena. This study has been aimed to investigate performance of wavelet-adaptive neuro-fuzzy inference system (wavelet-ANFIS) and adaptive neuro-fuzzy inference system (ANFIS) for simulation of rainfall-runoff process involved with snow water equivalent (SWE) in Latyan watershed located in Tehran province. For this reason, 92 MODIS images have provided by NASA website during three water years 2003-2005, snow cover area in all images has been extracted and finally SWE values have been calculated for the mentioned years. Also, the rainfall, temperature and discharge data for the mentioned years is available which has been used for modeling. The results showed that wavelet-ANFIS with rainfall, temperature and discharge inputs and 1-day delay these inputs with root mean (RMSE) of 0.006 and coeffficient of determination(R2) of 0.97 had more effeciency than ANFIS by grid partitioning with rainfall, temperature and discharge inputs with RMSE of 0.059 and R2 of 0.62 and ANFIS by subtractive clustering with rainfall, temperature and discharge inputs with RMSE of 0.059 and R2 of 0.65. The results Also showed that SWE involvement causes to increase the accuracy of models.