Journal of Water and Soil Conservation
Year:2014 | Volume:21 | Issue:4|Papers Count:25

There have been several models presented for evaluation and provision of the prevailing conditions of desertification. Two Iranian desertification models, namely MICD and IMDPA, were used to assess desertification hazard and select the best model for Sabzevar region. Firstly, work unit map (geomorphologic facies) was created using slope, geology, vegetation cover, land use, Landsat 5 satellite imagery and google earth data. Once scoring was at hand indicators, the relative hazard maps were produced. According to field observatories and incorporating advices from experienced connoisseurs of this field, ground truth map was prepared. In the next step, efficiency of the models was evaluated. In order to ascertain the level of compatibility between the hazard assessment maps produced by means of the MICD and IMDPA models and what was learned in the field, the Kappa index came to help. Differences between the frequencies of classes defined in the maps were investigated by applying the Chi-square test and along this, the most efficient model was chosen based on Kappa index as well as Spearman and Kendall’s correlations indices. Results from statistical comparison made between hazard assessment classes defined in the models and the ground truth showed significant differences (Pvalue<0.01). The matchup between the out results of models and the ground truth was evaluated as average to low extents. On the other hand, drawing an analogy between the Spearman and Kendall’s Correlation indices outcomes in each model and the ground truth showed comparable results in which the Kappa index and Chi square index was included, and this led to this conclusion that the MICD performs well above the IMDPA. Finally, the MICD was chosen as the efficient model.

In order to identify the minerals in bedrocks of shale, tuff, basalt and soils derived from these rocks, three soil profiles were dug in footslope position in three forest lands of Guilan province. Based on results, pyroxene, biotite, feldspar and smectitic clay minerals were dominant in shale. Higher amount of smectite has resulted in decrease in soil drainage and illuvial clays as well as increase in stress cutan. In tuff, Na-plagioclase exists in higher amount. However there was lower smectite in soils derived from tuff due to acidic pH, so higher illuvial clay were observed in substratum. In basalt, weathering process was prominent, because there were higher amount of Ca-plagioclase and mafic minerals such as pyroxene and olivine, hence higher amount of clay mineral production especially smectite was provided. Well-permeability in surface soils of basalt was an important factor for remarkable illuvial clay accumulation in sub-surface soils.

The objective of this research was to demonstrate the ability of canola to take up structural potassium from muscovite and biotite. The experiment was carried out in a completely randomized design with factorial combinations and three replicates. Culture medium was a mixture of sandy quartz and K-bearing minerals including muscovite or biotite with two sizes: <4 μm and 4-60μm (as silt) and the plants fed during a period of three-months by two different nutrient solutions (K+ and K–). At the end of the experiment, shoots were separated and their K content was determined with flame photometer. In- K treatment, total K uptake of plant was significantly influenced by the type of culture medium. The maximum K absorption was related to plants grown in culture medium containing biotite. However, the minimum value was observed in the muscovite and quartz bearing medium with K-free nutrient solution. Mineralogical results after treatment showed clay size biotite which was fed with K-free nutrient solution weathered more than silt sized biotite and partially transformed to vermiculite because in smaller size, the confinement layers of potassium are more weathered and will release their K more quickly and release it to the plant. On the contrary, there was no significant difference in the degree of muscovite weathering when fed with K+ and K– free nutrient solutions in both media. Muscovite was resistant in this situation

There are few reports about application of iron nano particles in remediation of contaminated soil. Thus, this study was conducted and focused on evaluation of iron nano particles efficiency for fixation of Pb2+ in soil. This experiment was carried out in the factorial experiment with completely randomized design with two types of iron nano particles including zero-valent iron and iron oxide (Fe2O3) with two times (3, 21 day) in three replications. Results from a sequential extraction showed that zero-valent iron nano particles (nZVI) significantly decreased water soluble/exchangeable Pb2+ and carbonate form from 3.6% and 40.0% in the untreated soil to 2.8% and 34.3% and concomitantly increased Pb2+ residual and organic matter form from 8.3% and 1.6% to 13.6% and 2.2%, respectively. In the presence of iron oxide nanoparticles, Pb2+ residual form significantly increased, whereas Pb2+ bounded with Mn/Fe oxide decreased from 48.7% to 44.5%. The extraction with EDTA was used to quantify the Pb availability in soil. Results showed that EDTA extractable Pb2+ significantly decreased in soil treated with nZVI, whereas, there is no significant difference between the nano iron oxide and untreated soil treatments. Moreover, in untreated soil Pb2+-EDTA increased significantly with time, while in case of other treatments it was not significant. Generally, it seems that the application of iron nanoparticle had not effective role in stabilization of lead in studied soil.

Unsuitable distribution, installation and maintenance costs for ground monitoring stations are issues in air pollution monitoring. Installed MODIS satellite on Aqua and Terra are able to identify aerosol optical depth (AOD) retrievals in troposphere and can be used for aerosol pollution monitoring in areas such as western Iran. In this study, MODIS level 3 data in Aqua and Terra were used to study the spatio-temporal distribution of aerosols over western Iran in 2000-2011. The results indicated that aerosols variations in Khuzestan Province is different and is much higher than other western Provinces of country. The AOD variation in western part of the country had decreasing trend over Ardabil, East Azerbaijan, West Azerbaijan, Qazvin, Gilan and Markazi Province whereas, AOD variation had increasing trend over Ilam, Khuzestan, Bushehr, Shahrekord, Zanjan, Kurdistan, Kermanshah, Kohkeluye and Boyerahmad, Lorestan and Hamedan Province. However, this trend in Khuzestan Province is significant (0.78±0.22). Khuzestan province has experienced high average of AOD in the period 2000-2011. According to the results obtained, AOD has decreasing trend from west to east and from south to north. Very high average was observed in summer season, particularly in southwestern Provinces such as Khuzestan, Bushehr and Ilam, but lower average was observed in autumn season. Based on the results of this study it seems that using MODIS Level 3 products is appropriate in order to evaluate the AOD spatio-temporal variation.

Rainfall erosivity index is the most important factor which impacts soil erosion. The objective of this research was mapping spatial and temporal variations of rainfall erosivity in the southwest of Iran. Properties of 10,000 rain storms belonging to 27 climatological stations were analyzed and their synthetic energy (E) and maximum 30 minute rainfall intensity (I30) were calculated. The mean annual and monthly rainfall erosivities were calculated for all stations' data. Mapping spatial variations was carried out using Spline algorithm. The results showed that the monthly erosivity index values decrease from the north to the south and from the west to the east of the region. Maximum and minimum values of annual erosivity were equal to 26.39 and 6.11 MJ.mm.ha-1.h-1.yr-1 belonging to Ivan (Ilam province) and Brojen stations (Chaharmal Va Bakhtiari province), respectively. Temporal studies of rainfall erosivity index indicated that maximum rainfall erosivity was equal to 183.7 MJ.mm.ha-1.h-1.yr-1 and occured in winter. Existence of significant correlation coefficients between the means of monthly and annual rainfall values and their corresponding rainfall erosivities were 0.94 and 0.93, respectively and such significant correlation coefficients facilitate indirect estimations of monthly and annual rainfall erosivities through rainfall values and simple or multiple regression models. The results revealed higher reliability of multiple regression models consist of both means of annual rainfall and rain storm intensities than simple regression models for estimation of annual rainfall erosivity.

Deforestation has detrimental effects on the watershed environment which resulted in increasing flooding and sediment yield. The aim of this study was to evaluate the effects of land use change on some selected factors of soil quality in the three land uses i.e. natural forest, planting and disturbed forest in Shastkalate watershed. 30 Samples were taken of 0-30 cm depth in a completely randomized design from three Land uses in hill physiographic unit. Chemical, physical and biological parameters of soil quality factors were analyzed. Analysis of data showed that with conversion of natural forest to disturbed forest, the amount of clay increased 13.5%, sand 46%, bulk density 18%, plasticity index 26%, Soil pH 6.64%, calcium carbonate 48.4% and available phosphorus 19.8%. The amount of silt decreased 22.7%, mean weighted diameter 24%, specific surface 29.6%, electrical conductivity 25.9%, organic carbon 64%, nitrogen 59%, cation exchange capacity 19.7% and microbial respiration 35% and planting could not compensate this statistically significant changes. The results showed conservation of forest lands can be the most important operation in soil conservation plan in the area. Although planting plan is used but this operation because of short time of settlement had no significant effect on soil properties and major effects need more time and long time studies.

Dam construction on the rivers causes sediment accumulation behind them. Determination of quantity and quality of sediment deposition in reservoirs is important for their stability and operation. Area- reduction method is one of the empirical methods for reservoir sediment distribution. In this method, reservoir is divided to four types, based on its shape. Parameters are presented for each types of reservoir which is carried out based on sediment distribution. Determination of suitable parameters in operating reservoirs which have at least one period of hydrographic data, leads to increment of accuracy. The objective of this research is to determine the optimal parameters of empirical area reduction method in Karaj dam using Shuffled Complex Evolution algorithm. In this research, a computer model was developed based on area reduction method theory. Then optimization model was prepared using Shuffled Complex Evolution algorithm and these two models were combined and Simulation-Optimization model was developed. Simulation- Optimization model determined area reduction method parameters for Karaj dam so that the most compatibility occurs between computational and measured volumes. To determine optimal parameters values, objective function was defined as Root Mean Square Error (RMSE) calculation of actual values. Using prepared model, optimal parameters were obtained based on information in 1961 and hydrography in 1991. To verify simulation-optimization model, sediment distribution in 2007 was calculated using obtained optimal parameters by model and was compared to hydrographic values. Results showed that values of objective function were reduced up to 62% and 48% in calibration and verification periods, respectively. Then, sediment distributions of Karaj dam were predicted based on optimal parameters.

Studying the phenomenon of frost and chilling is one of the fundamental researches in the field of Agroclimatelogy and knowing how and when they occur, could be useful significantly in the agricultural sector. Climate change which causes changes in temperature parameters influences the frost. To this end, a research was done so that the beginning of the first frost and chilling in autumn, the last frost and chilling in spring and also period of the frost and freezing at three weather stations in Tabriz, Qazvin and Mashhad would be checked during 1961-2005 as the basis period and during 2005-2050 as the future period. The data of the future period was produced based on output of Hadcm3, under the scenario A1B, using the software of data generator LASR-WG. Then time series of the dates of the first and last frost and chilling in autumn and spring was formed for each year during the periods of the study and the best statistic distribution was fitted for each of them and the possibilities of their happening were calculated. The results showed that at all stations affected by the climate change, the first frost and chilling in autumn will occur earlier and the last frost and chilling in spring will occur earlier and length of frost and chilling period will decrease.

The purpose of this study is to evaluate the SSIIM 3D mathematical for simulation of complex flow patterns. For this purpose, the flow field was simulated in a U shape channel bend with intake. Application of numerical model is necessary to reduce costs and to better understand the phenomena. In this paper, flow field in a U shape channel bend that lateral intake is located in outer bank at position 115° of channel bend 45 degree diversion angle is simulated by SSIIM 3D model. Numerical model has good ability to predict the streamline, velocity profile and flow pattern with an average error of approximately 3.84% but there are differences near bed, inner wall and outer wall and the average error is 9.63%. This defect is due to using k-e model. Further, prediction of secondary flow vectors is not in good agreement with observed data in main channel but the flow pattern at different cross-section has good accuracy in branch channel.

Numerous soil erosion models are developed and are applied in soil erosion studies as an acceptable feature in order overcome problem of lack of the adequate data on soil erosion and sediment yield. The Universal Soil Loss Equation (USLE) is one of the primitive empirical models in estimation of erosion that is used continuously. In this study, the accuracy of USLE model and some of its versions including MUSLE-E, MUSLE-S and AOF are evaluated in event-based in North Khorasan semi-arid regions. For this goal, the sediment due to 20 rainfall event is measured in experimental plots in Sanganeh soil conservation research Institute of Mashhad as a definitive of semi-arid rangelands of Khorasan. Then the erosion amount due to each rainfall event is estimated using selected various versions of USLE. Results obtained from application of each model compared with measured sediment values of selected plots and finally the accuracy and efficiency of mentioned models are evaluated. The obtained results of evaluation from 20 meters plots show a statistical relation and significant correlation between estimated amounts of MUSLE-E and MUSLE-S models and observed sediment. According to non-significant difference between models results and observation amounts of sediment (tMUSLE-E=1.53 and tMUSLE-S=1.63) and also lower statistics of RRMSE, efficiency of these two models in estimating erosion amount is also greater than the others. The USLE and AOF models cannot appropriately estimate observed sediment because they are not in good agreement.

Protecting the river bank by using groynes is very common in river engineering projects. Spur dikes makes flow path to be modified. Because of the concentration of flow in middle part of the river side is washed out. Settling spur dikes in the flowʼs direction lead to a local scour in the spur dike side and the change in the bed topography. In this investigation a laboratory movable bed flume with 18 m length, 1.5 m width and 0.8 m depth was used. To study local scour near the head of unsubmerged gabion groynes, the groynes were constructed perpendicular to the flumeʼs wall. Two shapes of groynes (L shape and T shape), two constriction ratios (20% and 30%) and four ratios of space to length (S/L), were used with one constant bed material and one constant bed slope with three different discharges. Since the reduction of flow velocity between two consequent groynes, causes sedimentation and bank protection, all of the experiment were repeated with constant bed. In this experiment the flow velocity and the pattern of streamlines between consequent groynes were investigated with more details. Based on the experiments result for L shape groyne S/L=3 and for T shape groyne S/L=4 is recommended as the most suitable S/L ratios. Regarding the type and shape of groyne, T shape groyne indicated the least scouring depth.

The flood hydrographs preparation is essential in order to provide the necessary information to control flood projects. However, getting access to accurate flood information is too difficult and expensive due to practical problems and the lack of suitable hydrometric stations. In addition, providing and analyzing unit hydrograph is considered as a usual and useful method for flood studies in watershed scale. Since the theories of making and applying the unit hydrograph cannot be provided, the investigation on the effects of mentioned theories and especially linearity and time stability on the precision of derived unit hydrograph is important. In spite the importance of variability of unit hydrograph, there are a few studies in this field. Towards this attempt, this study has been formulated in Kasilain watershed with the aim of investigating the unit hydrograph variability in different effective time bases using the hydrograph and hyetograph analysis of floods reports recorded during last 33 years. So that the range of differences between peak discharge, base time and time to peak of representative 2h unit hydrograph and those obtained from 0.25 to 6h unit hydrographs were found about 0.75 to 281, 6 to 36 and 0 to 50%, respectively.

Today, due to the decrease in water resources, the authorities intend to increase application of modern irrigation systems in farms and gardens. Therefore, evaluation and monitoring of drip irrigation systems are performed with the goal of improving systems performance. For this study, 20 samples of implemented drip irrigation systems in different cities of Golestan province have been studied in 2011-2012. The evaluation has been performed based on the guideline of Soil Conservation Service (SCS). Measurements in any field were included pressure and discharge of emitters, check the status of the central control, applied water, wetted area, water quality and talk to farmers about the state of the system strategy. The results showed that average amounts of emission uniformity (EU), statistical uniformity coefficient (UC), and efficiency reduction factor (ERF), potential application efficiency of low quarter (PELQ) and application efficiency of low quarter (AELQ) were 79. 85, 90, 65 and 73%, respectively showing that the performance of drip irrigation systems is average. In general, the main problems of drip irrigation systems in the province can be classified in four main categories based on, design, implementation, management and operation of social and natural division, in each of which the most important are design and improper implementation, lack of cleaning filters, clogging and improper number of emitters, not-adjustment of inlet valve on manifold, inappropriate pressure and its nonuniform distribution, low wetted area and extreme weakness in operation management by the users.

The quality of water is as important as its quantity in irrigation. Lack of wastewater purification plant in Rasht, Zarjoub River receives all municipal, industrial and agricultural wastewaters. In this study the effects of irrigation water from five stations along the river and irrigation water from well water on heavy metals accumulation in soil were assessed. A pot experiment was carried out in a completely randomized design with three replications. Irrigation regimes were flooding, saturated condition, field capacity (FC), 0.8FC and 0.6FC. Irrigation was done with water from five stations along the river and water from a well. After physiological maturity, harvest was done and soil heavy metals concentrations were measured with atomic absorption apparatus. Results showed that pot soils in all treatment were polluted with Cd and Cu (being in average higher than 0.3 and 50 mg/kg as maximum allowable concentrations, respectively) however Pb and Zn pollutions were not detected (being in average higher than 250 and 200 mg/kg as maximum allowable concentrations, respectively).

Municipal wastewater is a potential source for water supplies. Soil organic matter can affect chemical quality of wastewater passing through the soil. This experiment was carried out to determine the effects of different levels of vermicompost on change of chemical properties of Cd enriched municipal wastewater of Yasouj station after continuous passing through the soil columns. A completely randomized design was used. Polyethylene columns (80 cm in length and 8 cm in diameter) filled with a clay loam soil during 8 periods of 10 days. Three levels of vermicompost comprising control (V1), 2% (V2) and 4 wt% (V3), were used respectively. At the end of each period, characteristics such as pH, electrical conductivity, phosphate, nitrate, total organic carbon and cadmium concentration were measured in drainage water. Results showed that the effect of both the time and vermicompost was significant on all measured factors. The average of all factors except for pH of the drainage water, showed a decreasing trend during the experiment. Maximum of EC, P, nitrate and total organic carbon were measured in V3 treatment. Vermicompost exhibited a significant effect on Cd concentration of drainage water. It seems that organic matter has a drastic effect on increasing mobility of Cd as well as on the other studied characteristics, hence soil organic matter content should be considered in the usage management of wastewater.

One of the most important problems in determination of life expectancy of dams, are the rate and distribution of sediments in the reservoir. Mathematical models are recently used for simulation of the reservoir sedimentation rates and predicting life expectancy of the reservoir. These models are based on the analysis of governing equations of sediment transport, distribution, deposition and erosion. In this study, mathematical modeling of erosion and deposition of sediments in Satarkhan dam, has been studied using GSTARS 3.0 model. GSTARS mathematical model using stream tubes concept, has an ability to account for the longitudinal and lateral distribution of sediment deposition in the rivers and dams. For hydraulic and sediment calibration of this mathematical model, information of Satarkhan Dam and cross section between 1998 and 2009, have been used. Calibration results showed that Yang (1973) sediment transport equation had a good agreement with field data.