Journal of Water and Soil Conservation
Year:2013 | Volume:20 | Issue:3|Papers Count:16

Nowadays one of the solutions to protect aquifers in developed countries is to prevent contamination of aquifers. In this study Salafchegan-Neyzar Aquifer vulnerability against agricultural pollution was evaluated, by Drastic and GIS models. In this method, seven hydrogeological factors that were effective in groundwater pollution were combined. The seven factors are: watertable depth, the net recharge aquifer, aquifer media, soil media, topography and the unsaturated hydraulic conductivity. Vulnerability zoning maps were drawn from the results obtained. Zones vulnerable to nitrate pollution were determined. Using GIS techniques and by single-parameter sensitivity analysis, the influence of parameters used were investigated. Results showed that depth to water table aquifer of Salafchegan was the most important factor influencing vulnerability in Salafchegan-Neyzar aquifer. The results of different qualitative zones was shown in four categories of very low, low, medium, high which were 550, 853, 150 and 498 square kilometers before the correction of model were converted to 351, 486, 401 and 425 after the model correction. In general, sensitivity analysis showed that effective and theoretical weight of using parameters, aren’t fully coincide and in some cases have considerable differences.

Reference crop evapotranspiration (ETo) has important effects on estimation of agricultural water use, ecosystem models, aridity/humidity conditions and rainfall-runoff. Although, the accuracy of FAO Penman-Monteith (FPM) method for estimation of ETo in different regions was confirmed, but because of the requirements of many meteorological parameters, its applications was limited. In this research, by using 6 empirical and 5 semi-empirical equations, monthly ETo values were calculated during 1990-2007 for 12 synoptic stations in 4 climatic regions of Iran. By using FPM as a reference method and calculating monthly ETo values, empirical and semi-empirical equations were calibrated for the period 1990-2003. By using combined criteria IPE for the period from 2004 to 2007, the best equation of each station was determined in lack of any meteorological parameters. Calibration by using the best linear equation reduced the amount of errors in most equations and in most stations. Estimation of solar radiation via temperature data caused the precision of semi-empirical equations being lower than empirical equation in both “humid” and “warm and semi-arid” regions, but this criteria was higher in both “arid” and “semi-arid” regions. The effects of solar radiation on ETo was quite relevant in “humid” and “warm and semi-arid” regions., while its effects was inverse in arid and semi-arid regions which confirms the effects of temperature parameters in this regions. Selection of the best equation depends on which criteria of MBE, RMSE, MARE or R2 was considered as judgment. The combine criteria of IPE were weighted by four mentioned criteria and provided the condition of the best selection.

This research was carried out to detect the soil infiltration variability as affected by flood spreading in area of 42000 m2 in southern Dehloran during 2004-2007. The studied soil has no profile development and was classified as Entisols. Mean annual precipitation was 235.2 mm. After selection of experimental area and control, infiltration determinations by Kostiakov method were done (from 9 points with 3 replications) in each band as 1400 length and 300 widths. Decrease of water level in central core was determined in time intervals of 1, 2, 3, 5, 10, 15, 20, 25 and 30 minutes with three replications. Data were analyzed by t-test and non-parametric test of Kruskal Wallis by using SPSS and MSTAT software. In the last year (2007), results indicated that between bands and control sites, there were significant differences (in 5% level). Also base infiltrations in control and flood spreading places were 18.0 cm.hr-1 and 13.6 cm.hr-1, respectively. This was indicated that infiltration has reduced trend as affected by flood spreading. In first, second and third bands in comparison with control, there were 21%, 23.1% and 17.4% decrease in soil infiltration. Correlation matrix of parameters indicated that between physical and chemical properties, there were stronger relations between infiltration and soil particle size (sand, silt and clay) than other soil characteristics. SAR and EC did not have any effect on soil infiltration rates because of low amounts of those. So, decrease of soil infiltration was due to increase of clay and silt amounts.

During flooding, flow enters floodplains and extremely affects the hydraulics of river flow. In this case, estimation of flood discharge with traditional or commonly used methods leads to high errors (up to 40 percent). The most significant method for modifying traditional methods is Shiono and Knight quasi 2-D model which has numerous applications in laboratory and field compound cross sections. In this paper, based on this 2-D model, suitable dimensionless equations for secondary flow effects have been presented for solving the velocity lateral distribution in straight flume and river compound channels. Results of main channel flow velocity of this method have been compared with Shiono and Knight and Ervine et al., models, for some flume and river compound channels. This comparison showed that the proposed equations and Ervine et al. model had the highest and lowest accuracy, with determination coefficients of 0.99 and 0.71 percent, respectively. Also Ervine et al. method may lead to high error in case of asymmetrical compound cross sections and hence, it is not recommended.

Considering the importance of soil in supplying food for the increasing human population, knowledge of soil quality, including physical, chemical, biological and mineralogical properties are important. Spatial variability of soil properties is related to environmental factors such as climate, slope position, topography, slope gradient, elevation, parent material and vegetation. Topography variability and soil formation cause the significant differences in soil characteristics in a hillslope. The main objective of the present study was to assess some physical, chemical and biological indicators of soil quality in a loess hillslope of Toshan area in Golestan Province, Northen Iran. Therefore 135 samples were collected at random systematic method (0-20 cm depth) at three aspects and four slope positions. Soil texture, bulk density, organic carbon (OC), electrical conductivity, pH, microbial respiration rate, calcium carbonate equivalent (CCE) and mean weight diameter (MWD) of aggregates were measured for studying soil quality, including physical, chemical and biological. The results indicated that the lower slope positions had the highest amounts of clay, OC, MWD and the lowest CCE and soils in north-east aspect had higher OC compared to other aspects. Therefore, it is concluded that most soil properties are dependant largely on slope position and aspect that could have a long-term influence on soil development and evolution. Among the soil properties, OC is a suitable indicator for assessing the effects of slope position and aspect on soil quality in the studied area.

Accurate computation of flood discharge has specific priority for many river engineering projects and flood controls. In flood condition, by flow entering into the floodplains, hydraulic flow is more complex than usual. Recent studies have shown that existing methods do not have sufficient accuracy in calculation of flow discharge in time of flooding. Therefore, many modified methods have been proposed by various researchers. These methods are often time-consuming and sometimes need to use numerical solution of differential equations. In this paper, M5 decision tree model is proposed as a new solution for accurate computation of flow discharge in compound channels. Dimensionless variables of the flow depth ratio, coherence parameter and ratio of computed total flow discharge to bankful discharge have been used as input data and ratio of actual discharge to bankful discharge as output (target) variable. 400 stage-discharge data were collected from 30 experimental and natural compound channels and then divided into calibration and validation groups. Using decision tree model, four linear equations have been derived for calculation of flow discharge in compound channels based on depth ratio. By statistical comparison of results, determination coefficient (R2) and root mean square error (RMSE) were obtained as 0.939 and 0.382 for calibration data and 0.938 and 0.466 for validation data, respectively. The proposed method has more accuracy than the DCM, Ervine et al. (2000) and Haidera and Valentine (2002) methods.

Since the design of water systems in many countries such as Iran are according to water systems criteria of 50 years ago, this issue should be reconsidered on adaptability with atmospheric changes. Energy balance algorithm for the earth by using MODIS satellite images with interval of 10 days and spatial resolution of 250×250 meter was used, to estimate the amount of evaporation and transpiration of green landscape in Mellat Park of Mashhad. The evapotranspiration in Mellat park of Mashhad (per square meter) in the end of the growing season was about 1210.6 mm. In the other side, the values of reference evapotranspiration are calculated by the FAO 56 Penman-Monteith at the end of the growing season reached to 1563.3 mm, showing an increase of 22.5 percent compared to the estimated one. The relationship between evaporation and transpiration of the estimated plant was significant by FAO 56 Penman-Monteith in SEBAL Method, with the correlation coefficient of 0.7637. Using the relationship based on vegetation index is useful to make a connection between evaporation and transpiration of the estimated source plant (by method of FAO 56 Penman-Monteith) and the real evaporation and transpiration. RMSE and MAE decreased from 2.62 to 1.27 and 1.83 to 0.91 respectively. Therefore RMSE and MAE for the real estimated evaporation and transpiration was estimated by multiplying crop coefficients related to landscape and during entire growing season and was equal to 1.2 and 0.93 respectively.

Low quality water use for agricultural production is increasingly regarded as a solution for water scarcity, and also provide new sources of water for higher food production in the world. But its use could create environmental and health hazards and prevent to achieve sustainable agriculture. The objectives of this study are to investigate the extent and degree of heavy metal contamination (Cadmium (Cd), Nickel (Ni), Zinc (Zn), Copper (Cu) and Lead (Pb)) at 23 points along Zarjoob river in water, soils of paddy fields under its irrigation, and rice grains and straws (Hashemi var.) and also the relationship between heavy metals concentration and soil phsico-chemical properties (pH, CEC, texture, TNV, EC) and rice grain and straw were determined. The analytical results indicated measured heavy metals concentration in water, soil and plant tissues (except a numbers) are less than critical levels, however an increasing trend was found with river length (before city<city<after city) especially for lead, copper and cadmium in comparison with human health standard rates. The linear multiple regression equations indicated significant correlation of Cd, Zn and Cu with organic carbon and pH, Pb with clay content and pH, Ni with pH, concentration of Cu, Ni, Cd and Pb in 0-15 and 15-30 cm soil depth. No significant correlation was found between Cu, Ni, Cd, Zn and Pb concentration in water, soil and plant tissues. Comparing these data with last decade researches findings represent 3-4 times increase of theses heavy metals at plant tissues.

Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) are known to enhance plant growth and survival in heavy metal contaminated soils through different mechanisms. The objective of this study was to evaluate the enhancement of soil Pb extraction by Acroptilon repens through inoculation with some AMF (a mixture of Glomus species including G. intraradices, G. mosseaeand G. fasciculatum) and PGPR (a mixture of Pseudomonasspeciesincludeing P. putida, P. fluorescens, and P. aeruginosa). This study was carried out in greenhouse condition as a factorial experiment based on a randomized complete block design with two factors including Pb concentration (in four levels) and microbial treatment (in two levels) and in three replications. Consequently, a soil sample was selected and spiked uniformly with different concentrations of Pb (0, 250, 500 and 1000 mg Pb kg-1 soil). The contaminated soils were then sterilized and subsequently inoculated with AMF and PGPR. Results indicated that shoot biomass, Fe and Zn concentration in shoot decreased and bioavailable Pb, shoot Pb concentration and total Pb extracted by Acroptilon repens increased as soil Pb concentration increased. Inoculation with AMF and PGPR species increased shoot biomass of Acroptilon repens up to 2.7 and 1.4 times higher than control treatment, respectively. Pb extracted by shoots in AMF and PGPR treatments on the average was 3.2 and 2.2 times higher than control treatment, respectively. Therefore, it could be concluded that soil Pb extraction by Acroptilon repens enhances through inoculation with species of AMF and PGPR.

Water management and best use are among the topical issues and therefore the negative trends of water quality should be reduced. We have tested various water quality improvement scenarios in this research. We selected nine water quality factors and generated an initial set of 41 independent variables relating to landform, physical and biological plus landscape metrics of the surrounding environment of the rivers. Regression and correlation analyses helped narrow down the independent variables and define equations between dependent and independent variables. Five management items were devised based on the regression relationships and expert opinions including: decreasing fractal dimension of remnant tree patches, pasture extension onto bare land, decreasing area under agriculture based on a special multi-criteria analysis (MCE), decreasing road density based on a pattern suggested through least cost algorithm and increasing area under pasture management and the number of tree patches. To balance the results of the scenarios and select the optimum one, a multi-criteria approach was adopted during which the analytical hierarchy process was applied and the 32 scenarios were analyzed through technique for order preference by similarity to ideal solution (TOPSIS). The best scenario was found to be the one including road density decrease plus range extension onto bare land and decrease of fractal dimension of the remnant tree patches. These were the best in terms of the selected criteria for water quality improvement.

Temporal and spatial trend of water quality parameters were investigated in this study. These parameters were zoned according to agricultural and drinking water classifications using Booleans logic and GIS. Temporal trends for TDS, pH and EC were evaluated, and effect of different factors especially climate change were investigated in 3-year periods. The results showed that main factors affecting the temporal and spatial variations respectively were human activities, climate change, water temperature and transfer of pollutants from outside of the studied area.

Hydrocarbon pollutants with negative polluting effects cause changes on physical and chemical properties of soil and water and threaten their quality and human safety. The purpose of this research was to investigate the heavy and light soils behavior on transportation of gasoline and kerosene in a pilot scale and pulse condition. An equipment including glassy cylinders has been designed. The bulk density and porosity of the soils have been determined. Then, the amount of half and one pore volume, gasoline and kerosene were applied. Glassy cylinders were filled with soil homogeneously in the given depth and soils were saturated by water. In this stage, half and one pore volume of the kerosene and gasoline were applied on saturated soils. Eventually, output volume of gasoline, kerosene and water has been measured per time. Finally the breakthrough curve were drawn. The results showed that both pollutants went through the loamy sand soil by less retention and more velocity in comparison with silty clay one. In both soils, gasoline retention was more than kerosene and kerosene flowed out of the light and heavy soils by sharper gradient and less retardation and more velocity. This difference in the output rate of pollutants from light soil is more distinct than heavy one. The results of this investigation can be applied for pollution emission assessment in terms of pulse pollution and quality of soil reaction versus these pollutants.

The important problems in sustainable development of groundwater resources is its scientific management. Therefore in this research, using modflow software, the effect of irrigation efficiency increase on Urmia plain groundwater resources was investigated. Urmia plain groundwater model had been calibrated, and evaluated for the years 1992-1993 and 2000-2001. In this study, this model was reevaluated using different irrigation management scenarios and 28 pyzometers observed for the year 2008. The effect of the irrigation efficiency increase with decreasing recharge rate by 20, 40 and 60 percent in urmia plain model was studied. Modeling results showed that water level was fallen 25 cm, 50 cm and 75 cm with recharge decreasing rate of 20%, 40% and 60% respectively. Results showed that east regions and central part of the plain would face drainage problem. The model shows that many of unwanted problems can be solved by applying modern irrigation system and increasing the irrigation efficiencies instead of present traditional irrigation systems.

In this study, daily flow of the Chehelchai watershed was simulated using the Soil and Water Assessment Tool (SWAT) model. The main objective of this study was to evaluate the performance of SWAT model and the applicability of this model as a flow simulator at the Chehelchai watershed. In order to have a successful calibration, a process of parameters sensitivity analysis was performed and then calibration and validation of the model were performed using the recorded data of 7 years. The data from 2001 to 2004 was used for calibration and those of 2005 to 2007 for validation. The results of sensitivity analysis showed that soil evaporation compensation factor (esco), curve number (CN), soil available water capacity (sol-awc), deep aquifer percolation fraction (rchrg-dp) and soil bulk density (sol-bd) had the most influence on output of the model. During calibration, the simulated daily flow matched the observed values with a Nash-Sutcliffe coefficient of 0.57 and a coefficient of determination (R2) 0.62. These values were 0.32 and 0.42 during the validation. The results of simulation bases of monthly flow showed beter accuracy and good correspondence.

Land salinization and sodification is a serious problem for being human in arid and semiarid regions of the world. Salt affected soils are widely distributed in Iran and this study is aimed to assess the ameliorative effects of different materials for reclamation of sodic soils. In order to study the effects of gypsum and aluminum sulfate alone or with water soluble polymer, modified starch, nano clay and a combination of these materials on physical properties of a sodic soil, a factorial experiment with 18 treatments was conducted in Zanjan University using a completely randomized design and three replications. After addition of different treatments to soil samples, they were incubated for four months at moisture content of field capacity. The results of the experiment showed that the effects of gypsum, aluminum sulfate, modified starch, water soluble polymer with nano clay were significant on reducing dispersible clay content. The lowest amount of dispersible clay was measured in treatment with 75 kg ha-1 water soluble polymer+75 kg ha-1 modified starch+2% nano clay and along with aluminum sulfate equivalent to gypsum requirement of the soil. This treatment reduced the amount of dispersible clay from %95 in control to %3.4. In contrast, the highest amount of water dispersible clay was shown in control treatment.