نشریه پژوهش های آبخیزداری
پیاپی 103 (تابستان 1393)

Direct measurement of cation exchange capacity and bulk density parameters is hard and costly; ýhenceforth indirect methods of pedotransfer functions for predicting soil parameters are developed ýbased on easily obtained parameters. In this regard, for estimating the cation exchange capacity and ýbulk density 63 samples were taken from 15 profiles in FASHAND zone in TEHRAN. Using ýpedotransfer function and having cation exchange capacity and bulk density as output variables, ývariablesthe normality of the input data were controlled by MINITAB software based on ýKOLOMOROF-SMIRNOV normality test. For developing the pedotransfer functions multiple ýregression and artificial neural network methods were enaged. Determining test and training dataþ þand then finding the best type of neural network, a hidden layer with 2 to 10 neurons was selected ýfor an optimum simulation in terms of RMSA, ME and AARE indices. Input data to the network ýfor predicting cation exchange capacity involved clay, silt, sand and organic material in percent ýwhile for predicting bulk densityþ þclay, silt, sand, lime, saturation moisture and organic material in ýpercent were selected. Using multiple regrsion techniques and some experimental equations like ýBreeuwsma and teammates (1986), Matrique and Bell (1991) andvanKeulen (1995) regression ýequations were developed. Because of nonlinear relationship between input and output variables, ýneural networks had better performance in comparison with the regression models which for ýcation exchange capacity and bulk density gave coefficient of determination as 0.89 and 0.74, ýrespectively. Regarding pedotransfer functions employed for estimating cation exchange capacity ýMatrique et al. (1991) models with a coefficient determination of 0.24 gave the same response ýwhich in comparison with the Breeuwsma (1986) models of a determination coefficient of 0.06 is ýmore acceptable.ý

One of the most important parameter of soil erosion is soil erodiblity. Soil erodiblity (K-USLE) plays the main role in mathematical function of erosion models as well as Universal Soil Loss Equation (USLE). In recent paper, the objectives are including determination the spatial pattern of soil erodibility of USLE in part of Yazd Ardakan plain as a typical arid plain of center of Iran and comparison and evaluation the kinds of kriging interpolation procedure consist simple, ordinary and universal. Soil was sampled in 37 points from 0-10 cm soil depth in almost uniform distribution by random classification sampling pattern. Infiltration was determined by double ring method. Soil samples were analyzed in laboratory with standard methods consist grain size distribution and organic matter. Soil erodiblity was calculated by method of Wischmeier and Smith. Normality test was carried out. ArcGIS 9.3 was applied to determine the spatial pattern of K-USLE and the effective parameters using simple, ordinary, universal and Inverse Distance Weighting (IDW) interpolation methods. MAE (Mean Absolute Error), MBE (Mean Bias Error), RMSE (Root Mean Square Error) and RI (Relative Improvement) were calculated for evaluation the interpolation procedures. K-USLE were varied at about 0.0055±0.0072, 0.005±0.0037 and 0.0173±0.0133 ton.hr/MJ.mm in fine, medium and coarse gravely plains, respectively. The result shows Gaussian model was fitted on ordinary kriging as well as spherical was applied for simple and universal kriging. In addition, the result shows the ordinary kiriging have the minimum bias in compare to the else interpolating procedures. Finally, the kriging procedures are more accurate and precision than IDW.

The ability of a watershed model to predict the channel flow, appropriately, for particular applications will be assessed by calibration, validation and sensitivity analysis. In this study SWAT model was applied to simulate runoff in the Kachik watershed with an area about 3600 hectares in Golestan province. For doing this purpose, the sensitivity analysis using sensitivity analysis tool SWAT2009 were performed due to availability of this tool in model software. Results showed that threshold height of water in the shallow water table that needs to be done back (GWQMN), curve number (CN2), soil evaporation compensation (ESCO), available water capacity of the soil layer (SOL_AWC), soil hydraulic conductivity at saturation (SOL_K) were most important factors controlling the flow rate in the studied watershed. Secondly, SWAT2009 model performance evaluation through the calibration and validation was performed. Data 2004 was selected as calibration period and 2005 and 2006 were determined as validation period. The results of model evaluation have illustrated that determination coefficient of calibration and validation periods are 0.71 and 0.75 and coefficient of Nash-Sutcklief are 0.70 and 0.71. So we can conclude that the SWAT model can predict surface runoff with high precision.

Floodwater spreading is an efficient and appropriate method for the optimization of runoff utilization, particularly in arid and semiarid region. Beside the reduction of damage caused by the floodwater, this technique would also be useful in the artificial recharge of groundwater, rangeland rehabilitation and desertification control. This research was conducted on the effects of floodwater spreading on some of the characteristics of vegetation and soil surface parameters. Two key areas were selected within and outside floodwater spreading in the Sarchhan plain. In this study, are investigated the effects of flood water spreading on the quality(regeneration, vitality) and quantity of pasture cover in Sarchahan Flood spreading station at 90 km north of Bandar Abbas. For this purpose two areas were chosen a part of the water spreading as a treatment and a similar areas in terms of vegetation cover and soil that it just not flood as a control. The vegetation cover items were recorded in 60 plats for water spreading area and 12 plats for control by 2×2 m during 4 years. This area is with a poor range condition and negative trend. In this study percentage of vegetation cover, density and forage production of rangeland plants were measured at water spreading and control area. ANOVA test showed based on quantitative variation there is significant differences between percentage cover (P>0.01) in flood spreading and control areas. But there is no significant difference between density, productivity and frequency factors. The effects of flood spreading on increasing procreation freshness of rangeland vegetation cover are apparent first in annual spices then perennial species later with changing in other environmental factors as soil.

Ranges are composed of different species, each of them having its own phonology and dimensions. Knowledge of these species characteristics are important in rangeland management. The aim of the study was to determine the Phenological stages and resize of two species of Stipa barbata Dest and Stipa caucasica Schmalh in Nodoushan steppe rangelands of Yazd during the period of 4 years (2007-2010). First, for each species, 10 individuals per plant species were identified within the enclosure and in the study process of this plants were inventoried. Any information phenological stages and dimensions at intervals of 15 days and 7 days, respectively, were measured at vegetative and reproductive stages. Based on these results, the growth of Stipa barbata starts from the Third decade of January. Flowering occurs during the Third decade of April to First decade of May. seed ripening stage of this species in the study area occurs during the Third decade of May to second decade of Jun. Maximum canopy height was 91 cm, which is owned by the Relatively dry year, 2010, and at least it was 23 cm, which is related to the very dry year, 2008,and this difference is significant. Maximum and minimum canopy diameter were respectively 43 cm (in Common year, 2009) and 32 cm (in very dry year, 2008) and the differences are significant (P≤0.05). Canopy diameter in a relatively dry year (2010), Common (2009) and wet year (2007) was not significantly different (P≤0.05). growth of Stipa caucasica starts from the third decade of January. Flowering plants occur in the second decade April to the first decade of May This seed ripening stage is the third decade of May to first decade of Jun. Maximum canopy height was 38 cm, which is owned by the Relatively dry year, 2010, and at least it was 12 cm, which is related to the very dry year, 2008, and this difference is significant. Canopy diameter in a relatively dry year (2010), Common (2009) and wet year (2007) was not significantly different (P≤0.05). Maximum and minimum canopy diameter were respectively 34 cm (Relatively dry year, 2010) and 27 cm (in very dry year, 2008) and the differences are significant (P≤0.05).

This research was performed in the watersheds of Evan in Ilam province. Flood hydrograph was simulated by using HEC HMS model in HECGEO HMS and ARC MAP9.3 software. To this purpose¡ data of flood, discharge, daily and hourly rainfall were used in the 30 years period (1981-2011). Then all watersheds was divided to 4 smaller unit (E1, E2, E3, E4) and the maps were prepared like topography, vegetation, hydrologic soil groups in ARC MAP environment. The next step land use and hydrological soil group maps were combined and the result was CN map. As a result, E2 has the most runoff, On the other hand, the participation rate of sub areas in runoff aren’t direct relationship with area. Average cure number is 80 for sub area of study and this is significant cure number that showed that every rain, lots of its volume is flowing in the ground. Increasing height of runoff displayed that more changes in soil, waste of Plant available water in this area. This result is following changing land use from forest to grassland.

Nowadays, multi-criteria decision-making methods have found wide application in various sciences. Integrating GIS and multi-criteria decision-making methods has been lead to provide spatial multi-criteria decision-making methods. In this study, using analytic network process (ANP) the flooding spatial potential was determined. At first for this purpose topography, climatic, geology, soil, hydrology, landuse and vegetation factors identified as important factors affecting on flooding and were prepared related classes layers with these factors. Then the criteria and their classes were weighted by using analytic network process and was flooding spatial potential map in Ilwis 3 software was calculated through the combination of weighting layers. Our results showed that the average of flooding potential in Control subbasin was calculated 0.25 and in Sample subbasin 0.21. So the curve number factor have the greatest impact on flooding and has a direct relationship with that. Also the north slope has the lowest impact on flooding. This results showed the analytic network process can be used as a way to estimate the flooding potential and displaying the spatial variations in watershed.

Application of the vortex settling basins is one of the methods for controlling suspended sediments in the water structures. In this paper, considering the accumulation of the sediments at the floor of the vortex settling basin during sediment extracting, curvature submerged vanes in 90o radial section were used at the floor of the vortex basin and the effect of the size of the orifice was studied on the performance of the curvature submerged vanes for sediment leaching of the floor of the basin. Experiments were performed on a physical model with a height of 90 cm and a diameter of 2.06 m and a floor slope of 10% and also three orifices were used with diameters of 59, 46 and 36 mm. The submerged vanes were placed at different arrangements. The results of the experiments indicated that the performance of the vanes in sediment extracting of the floor is primarily influenced by the orifice and the arrangements of the vanes’ placements. It was also found that sediment removal will increase 20.03% if vanes position on the floor is in the best arrangement.

The purpose of this research was to study the irrigation period to plant growth. The statistic design was split plot method. To done this research prepare hold dig to deep and diameter 130 and 80 centimeter, respectively and experimented three factors, irrigation period (70 and 90% depletion soil water), soil (modify soil and control soil) and plant (Tamarix and Eucalyptus). This research done with split plat method with 8 treatments and 4 replications.
The results show that the irrigation period, soil and plant had effective on plants high in first year, but other parameters had no role. Irrigation period and plant were effective on plant high in 5% level and irrigation period, while the other parameters had no effective on this factor in second year.
Combine analysis show that the irrigation period, year and soil, irrigation period and plant kind had significant effects on plants on (1%) level. The research shows that the Eucalyptus and Tamarix grow with supply litter water in 70 depletion soil water 0.24 and 0.19 cm, respectively. While, this plants were grow in 90 depletion soil water period 0.11 and 014 cm, respectively. Therefore, the 70 depletion soil water period and modify soil were better than 90 depletion soil water period.

Quantitative analysis of ecological relationships between vegetation and the environment has become an essential means in the field of research of modern vegetation ecology. The main of this study using the numerical method for Individuation plots for the formation of phyto sociology units and comparing these methods in east rangeland of Semnan. Sampling of vegetation was performed in 270 plots using randomized systematic method. Sampling was done within each unit of sampling parallel transects and 1 vertical transect with 750m length, each containing 15 quadrates (according to vegetation variations) with a distance of 50 m from each other, were established. Quadrate size was determined for each vegetation type using the minimal area method. Vegetation data including density and cover percentage were estimated quantitatively within each quadrat. In this study separation of plots based on Euclidian distance and using TWINSPAN analysis, Cluster analysis and Indicator species analysis in order to classify vegetation. Indicator species analysis accompanied with Monte Carlo test was used to choose the optimum number of the clusters. Results showed that if six clusters were selected in the vegetation classification of vegetation communities in the study area based on cluster analysis, the number of indicator species, which had significant indicator values, would be maximum. Therefore, six groups could be introduced as the optimum number of ecological groups of east rangeland of Semnan. TWINSPAN analysis was used for classification, is better than other by higher eighen value (0.65 until 0.85) and DCA analysis was better than CCA Axis 1 and axis 2 were highly associated (0.63,0.193).

To evaluate the vegetative and productive characteristics and forage consumption by livestock at different stages of Bromus tomentellus phonology, this experiment was carried out during five years in Urmia-Garebagh rangelands. Thus starting the grazing season and livestock entering, any remaining amount of forage grazing was harvested until a month intervals, and consumption 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 consumption of species under investigation in the study area, data were analyzed. ANOVA combined data showed that overall because of hot weather in 87 and 89 the second and fourth year was highest production years and sixth month of forage production (biomass) was the lowest production through the months, but the second month has highest consumption of the grazing season.

Gully erosion is one of the developed features of accelerated soil erosion which is known as a geomorphic threshold phenomenon and controlled by different environment factors. This erosion type is formed in semi arid mountains that are not covered by plants. This paper tries to present internal environmental factors affecting on formation and expansion of the gullies. 42 gullies were selected to measure their morphometric characteristics in three regions including: Dehdasht, Brazjan and savadkooh. The height, depth, width and length of gully erosion were measured; then gullies were classified based on length parameter. For analysis data, Statistical comparisons were done between morphometric parameters and input factors (topographical and Physical – chemical factors) using F test; if significant the means were compared using Lsd test. The result showed that the gullies in two regions of savadkooh in Mazandaran province, and Dehdasht in Kkohgiluyeh va Buye ahmad province are the most similar and Brazjan region in Bushehr province is significantly different in most morphometric and physical-chemical characteristics with other regions (P

After identification of the species’ site in Shazand, Arak, samples of aerial parts and litter were ýcollected randomly and systematically in the known sites at the end of the growing season ýý(summer) so that for analyzing the features of these species, 10 plots were installed along 4 ýtransects. After data gathering, they were analyzed by the independent T. test and the variance ýanalysis test. The Comparison of the aerial parts and the litter in the range species, analyzed in ýthis study, showed that there was a signification difference between OM, C & ADF ratios in the ýaerial parts and the litter of these species. Quantitatively, the amount of N, C, OM, P, C/N in the ýlitter was more than the aerial parts, whereas, the amount of k in the aerial parts was more than ýthe litter. As a whole, in Astragalus ammodendron, the ratio of C to N was the least among the ýother species, so the quality of its litter, aerial parts, and soil amendment was much better.ý

The effective energy for erosion is called rainfall erosivity, which is rainfall erosion potential and depends on ýrainfall physical characteristics. Different indices have been developed to quantify the rainfall erosivity. In this ýresearch, study fields were conducted in Kermanshah provinces. The study site was Kaboudeh soil conservation ýresearch station and two types of land uses were selected for the study including 24 established runoff and sediment ýplots. The sites were equipped with digital rain gauges, thus necessary rainfall data were collected and used. Based ýon literature review, 11 rainfall erosivity indices were identified to fit more for erosivity so their efficiency were ýchecked on the study. Best erosivity indices were selected by determination of correlation coefficient between the ýamount of erosion in each single storm and calculated rainfall erosivity indices. The results indicated that the best ýindex for the study sites was EI60 and AI30 that has maximum correlation coefficient with soil loss.

The purpose of this study was to determine the Evaluation of different cutting intensity on some attributes of Teucrium polium and Helichrysum globiferum Gharebagh key species. In this first region and two key area of half hectare in area Gharebagh and in the first year and was grazed, and fencing. Selected and removed from any of 0, 25, 50, 75% and control is exercised (a basic 10 treatments). Monthly by the clipper and the area is grazing season. Effective utilization of changes in the phenological characteristics, forage and seed production, vitality, mortality and other characteristics of selected plants species were studied. Finally, the combined analysis of data from yield and vigority with a split plot design in SAS software was analyzed. Results of studies of the effects on forage production and harvest of T. polium and H. globiferum Gharebagh species studied showed that effects of different levels, different years, and their interactions on the production level is a significant percentage (p

Water harvesting and increasing moisture project are implemented for various tarrgets. In arid areas that water shortage is the major limitation factor for vegetation cover development, every work for increasing moisture and precipitation storage can be the cause of vegetation cover improvement. In this research the effects of crescent like-micro cachment as one of these project on functional characteristics of vegetation cover specially on key species 11years was investigated. For this purpose in each portion by means of control and implementig site as representatives of treatments was identified. In every ereas 14 transect with 400meters longs and on each transect 2 plot 8 m2 was established. After record of species list that had presented into the frame, characteristics such as canoy percent, number, plant size and litter was recorded separately. Compreffion by use of independent t-test was taken place respectively. Results showed canopy Implementing piece from 11/9 to 20.56 percent, production from 3.18 to 5.23 gr/m2 litter from 0.8 to 1.29 gr/m2 have reached. Also results showed increasing canopy, density, volume of stand live mels of Artemisia santolina species and decrease invasion species, Hammada salicornica difference total canopy, key species canopy, dry matter production and litter in 0.05 was significant due to implementing of this project. In other side variations of density and volume of stand live mass of this species showd significant difference in %1 respectively. In plant composition the portion of key species has been increased and protion of invesion species has been decreased respectively.

Fresh water is becoming a scarce resource of the arid region. The only option left to ýmanage with this situation is to conserve water resources. Since the amount of rainfall and ýevapotranspiration rate vary within a watershed, available water for surface and ýgroundwater recharge also varies both on spatial and temporal scales. Moreover, ýgroundwater recharge (and ultimately the total water yield) is directly influenced by the ýsoil texture and land cover in the watershed.ý
In this study, the distributed Thornthwaite-Mather water balance model for the Yazd-ýArdakan catchment in Iran was developed based on monthly precipitation, potential ýevapotranspiration maps and water holding capacity map. The amount of annual runoff ýfrom the catchment predicted by the model is 66.7 mmþ,þý which is accumulated in the plain ýand then salt desert. Half of discharge is contributed by the direct runoff and the ýgroundwater contribution is significant.ý
A statistical comparison of the estimated and the measured stream flow of Pishkouh show ýthe mean monthly and mean annual estimated and measured stream flows, the correlation ýcoefficient between measured and estimated stream flows, the mean monthly and annual ýpercentage error of estimation and the 90% confidence interval for the mean stream flow. ýSince the study of water balance using the TM method with the help of remote sensing ýand GIS was found to be very helpful in determining the amount of monthly runoff in an ýarid region like the Yazd-Ardakan catchment.ý