Watershed Management Research
Year:2015 | Volume:28 | Issue:108|Papers Count:10

In designing the stilling basin is trying to jump as close as possible to deal overflow, without affecting the flow of the weir is formed. In other words, to prevent the escape jump. For this purpose, the dissipation variety of water-Such as foam blocks and foam baths and foot spillway is used in sill. And thus reduced the length of the basin And is closer to the heel the spillway. In this study, to reduce the distance spillovers paws to start jumping from block foam blocks composed of 8 different forms were used. In these experiments, the spillway ogee with three heights (6, 5 and 4 cm) and for each spillway 4 slope (0.0 and 0.010 and 0.007 and 0.005) and for each slope 6 Dubai for Discharge 8 obstacles with different shapes were examined. The results showed that the total utilization of foam blocks in the stilling basin depth decreases, the distance between the top of spillway toe jump, the length jump and increase energy loss and improve the properties of hydraulic jump will be. In between shapes, the floor prevents the w90 is most effective. So that the spillway distance between the toe to jump start to a 65% reduction is unobstructed.

Determination of groundwater quality is an important issue in watershed management. The aim of this study was to investigate the spatial variability of some properties of Kerman groundwater using geostatistical methods. For this, groundwater quality data including soluble calcium, magnesium, sodium, bicarbonates, sulphates, pH, EC, SAR, TDS and TH for spring season of 2009 were collected. Interpolation analysis was done using Kriging, Co-Kriging, inverse distance weight (IDW) and normal distance weight (NDW) methods. The best interpolation method was chosen through root mean square error, mean absolute error and Pearson’s coefficient parameters. Result showed that the best fitted model for magnesium and pH was linear to sill, whereas for the other groundwater properties the Gaussian’s model was the best. Spatial dependency for bicarbonates and pH was moderate, while for the other ones, strong dependencies were observed. The result also indicated that for all the groundwater properties, Kriging with the Pearson’s coefficient ranging from 0.695 to 0.851 was the best algorithm. In addition to Kriging, the NDW and IDW methods found to be appropriate for the estimation of all the parameters except for EC and TDS. For these two latter ones, additional to Krging, the Co-Kriging method led to suitable estimates. The prepared maps showed that the amounts of bicarbonates and pH were higher at the north and south sides of the study area, respectively.The amounts of the other properties were minimum at the east and north east, while increased toward the west and south west.

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.

The study was located in Dasht Abkan, Padagan Kash, Dorahi Kosheh and Scale Abad regions of the Kash city. For this research selected and made fence a plot land (1 hectare) in each region. Two soil samples were collected from layers (0-45 and>45 centimeter depth) of each position, and analyzed for pH, EC, ESP, CaCo3, carbon organic, potassium, phosphor and calcium characteristics. Range-gauge has been put at each position for measure rain daily.We put 4 transect and each 10m establishment 1×1m plat. The parameters measured such as canopy, high of plant, diameter of plant, stem density, soil bare percentage, stone cover percentage, number dry species and number planting. To estimate of regression coefficient and Correlate coefficient data were analyzed by SPSS and MSTATC program, respectively. The result shows that annul average forage product (1996 -2003) in mention area were 172.8, 92.3, 67.1and 97.5 Kg/ha, respectively. In addition, the result shows that the between forage product and variances of soil have been high correlation index with K (P=0.073, R=0.886) and sand (P=0.230, R=0.728) percentage, Moreover have high correlation index with C (P=0.039, R=0.928) and P (P=0.001, R=0.993) and t have significant relation with it.In addition, the regression coefficient shows that the calcium, sand and ESP in forage product has effects in, Padagan Kash, Dasht Abkan, Dorahi Kosheh and Scale Abad regions, respectively.

The purpose of this study is to model the distribution of grassland habitats province of Chaharbagh. To this end, sampling of vegetation was systematic-random method that at each site three transects of 50 m was considered.Along each transect, 10 plots of one square meter was placed at a distance of 5 meters.30 plots in each vegetation type and total of 150 plots were carried out. The soil samples were taken at a depth of 0-30 cm. Soil characteristics include the amount of sand, clay content, silt content, lime, gypsum, Ec, pH, electrical conductivity was measured and physiographic factors of slope, aspect and elevation were recorded. After collecting data using logistic regression, the relationship between the plant types and environmental factors were assessed. For predictive mapping of vegetation is necessary to prepare maps of all the factors included in the models, so we used geostatistical methods for mapping soil properties. By the design of the models, with the help of GIS, the predicted distribution maps for each species were obtained. To evaluate the fit of the model predictions with actual map vegetation types, was used kappa index. The coefficient of Artemisia aucheri type equale. 0.80, The type Festuca.ovina-Astragalus.gossypinus equale ./98, Bromus. tomentellus type equale. 0.61 And the type Bromus.tomentellus-Festuca. ovina equale. 0.57 this model showed The type Festuca.ovina-Astragalus. gossypinus had the most accuracy and Bromus.tomentellus-Festuca. ovina type had the least accuracy in the production of habitat maps.

The saturated hydraulic conductivity is one of the most important and widely used geotechnical parameters. This parameter depends on properties of the fluid, pore size distribution, and characteristics of the solid surfaces. Because the latter two are not necessarily constant, the hydraulic conductivity may vary significantly. So far several empirical relationships for estimation of the hydraulic permeability with respect to the type of materials have been presented.In this research seven applicable method including Terzaghi, Kozeny-Carman, Chapuis and Aubertin, modified Navfac, Shahabi et al., Mbonimpa et al. and Chapuis were evaluated. Four samples of sandy soils (R1 to R4) with a rather wide range of particle sizes were prepared and were compacted within the Plexiglas box. After providing the head of 0.5, 1 and 1.5 meters; flow discharge and static pressure were measured which result phreatic and isopotential lines extraction. By applying the results of the model, the accuracy of some common methods used in the estimation of saturated hydraulic conductivity of sandy soils was evaluated. For the samples (R1 to R4), the coefficient of permeability was 0.0051, 0.048, 0.076, and 0.19 cm/s respectively. Due to the limited range of input parameters, the method of Shahabi et al. can be used only for the R4 sample; so this method was discarded from statistical analysis. Comparing the results of laboratory test with common methods shows the methods of Kozeny-Carman and Chapuis and Aubertin were more accurate according to the highest R2 and lowest RE and RMSE.These methods were based on effective parameters and the results of accurate laboratory studies. The method of Mbonimpa et al. (2002) indicates the maximum deviation from observed values which may be due to the sensitivity of this model to void ratio (e). Also the results shows by increasing of void ratio the error of Mbonimpa et al. method increases.

In studies of the effects of grazing on pasture plants, shoots and underground properties should be checked simultaneously. So the impact of different grazing intensities on the biomass of Festuca ovina species and the relationship between shoot and root biomass examined in Bijar protected area. After determining three grazing treatments with similar topographic characteristics, sampling of vegetation was done in random- systematically using 1 × 1 m plots within the 2 transects with 100 m in each treatments. Linear regression was extending to determining the relation between aboveground biomass and belowground biomass in each treatment. Statistical analyses were conducted by ANOVA. The result showed strong linear relationships between aboveground and belowground biomass in all the treatments. In addition with grazing intensity, relative contribution of aboveground biomass and belowground biomass were decreased and increased respectively. Relative proportion of aboveground biomass was significantly more in heavy grazing (67%) than both none and moderate grazing treatments (63% and 61.5% respectively). In addition relative contribution of belowground biomass was lower in heavy grazing treatment (33%) and it was 38.4 and 37.0% for moderate and none grazing treatments. The results indicate that grazing caused a significantly reduced effect on shoots and underground biomass.Heavy grazing and light grazing reduced below ground biomass (83.1 and 51.1%) compared to the none grazing area. Total biomass in grazed treatments, moderate grazing and heavy grazing was estimated at 69.7, 64.3 and 48.1 kg/ha. In general, different intensities of grazing effects on shoot biomass decreased, especially underground organs of this species. It is essential for administrators to protect the soil and prevent the death of this important species.

The structural and functional characteristics of fertilized patches in Bozdaghy rangeland, in North-Khorasan Province was measured and analyzed in this study. A group of measurable and simple indices of landscape function analysis (LFA) methods were used to evaluate these characteristics. The data were measured from seven land unit which is developed from overlaying of geology map on the dem and slope map. In this research the length and width of ecological patches by the forms of Grass, forb, shrub and bare soil with litter measured. Also we measured the 11 soil surface parameters on three, 50 meters transects in the seven mentioned regions. These 11 parameters are belonging to 3 major attributes of soil: Stability, infiltration and nutrients. Stability index is in u3 and u6, respectively, most (52.41) and lowest (38.1). Infiltration index is in u3 and u7, respectively, most (33.38) and lowest (24.39). Nutrient cycle index is in u2 and u1, respectively, most (24.38) and lowest (12.41). shrub was the most important ecological indicators of areas.

Various erosion models have been introduced since the beginning of the 20th century. However, application of these empirical models has been limited to specific climatic and geographical conditions. In the previous models, a method was developed to assess soil erosion based on land use information. In this paper, we present another approach that uses environmental data to assess soil erosion. This article presents one of these efforts in applying Analytic Hierarchy Process (AHP) which has shown promising results in estimation of soil erosion. In this regard, total six criteria (vegetation, soil, topography, land use, climatology, geology) and sixteen indicators (percentage coverage vegetation, growing forms, soil texture, infiltration, organic matter, slope, aspect, land use, type of precipitation, average annual rainfall and lithology) were considered. The weight of each thematic layer is determined through the AHP technique. This model is then applied in predicting soil erosion. The results indicate that the presented methodology is practicable for establishing a risk assessment model for soil erosion.

One of the consequences and envirinmental problem of changes in land use and land cover is soil erosion that threaten soil and water resources of watershed seriously.Therefore it is necessary that the spatial dimensions of land use and land cover are identified regularly so that the policy makers and researched able to take the necessary decisions. In recent years, due to easy access to satellite imagery and capabilities of GIS, land use and land cover changes modeling and prediction is very common. This study has been done to investigate the land use and land cover changes in Chaloos river watershed in Mazandaran province using CA-Markov and modeling of these changes on sediment yield. Estimation of erosion and sediment has been done using the results of land use and land cover changes and EPM model. Results showed that the rate of forest changes in the last 20 years and coming 20 years are 5100 and 4200 respectively. Results of logistic regression with Pseudo R2 0.3 and ROC about 0.9 represents the relative agreement of the model with actual changes and the appropriate ability of the model for estimating changes in forest area in last 20 years. Results about simulation of land cover map in 2001 and 2007 showed that CA-Markov has a high ability and capability in land cover changes modeling which in this study the accuracy of resulting land cover map was 80%. The results also show that the rate of erosion in 1987, 2001 and 2007 are 0.36, 0.38 and 0.39 respectively. It is observed that the trend of erosion is increasingly, but since beside the erosion rate, the temperature and rainfall also affects erosion, the rate of specific erosion in these years are 400.9, 400.9 and 363.6 cubic meter per square kilometer per year respectively, hence the the year of 2007 with further erosion rate has less specific erosion because the rainfall is less.