مجله تحقیقات آب و خاک ایران
سال چهل و هفتم شماره 1 (پیاپی 24، فروردین و اردیبهشت 1395)

The aim of this study was soil and clay mineral diversity in alluvial soils of Karoon River. For this, 14 profiles were described on transect perpendicular to the direction of eastern Karoon River bank. These profiles has 1 Kilometer distance and have different drainage and land use. The results show that soil salinity increased and OM decreased with increasing distance from Karoon bank. It was refer to drainage class changes. Ochric epipedon was diagnostic in all pedons. The subsurface horizons were restricted to cambic and salic horizons. The cambic horizon was formed due to wetting and drying under irrigation or rain, due to this crack and cleavage was formed in subsoils. Also, salic horizons was formed under high saline water table. Chlorite, illite, kaolinite, vermiculite, smectite, and quartz were identified by XRD. Kaolinite, illite, chlorite, and quartz was inherited from parent material. Vermiculite was formed from illite simple transformation due to cultivation and K depletion in soil surface near River bank. Also, smectite was formed in surface of this pedon. These clay were not seen in subsurface of these soils. Illite and chlorite intensity was decreased in surface that this was refer to transformation to vermiculite and smectite. In spite of first pedon, these clay mineral was identified in subsurface soil. This clay mineral was related to high pH, salinity, and Mg concentration in ground water. More study show that this smectite is trioctahedral.

This research was carried out in two grwoing seasons of 2010 and 2011 in Jiroft City aiming at investigating different irrigation water level and the pattern of drip irrigation system on greenhouse cucumber. The research was done as a split-split-plot design with 16 treatments and three replications by combining the main and the sub-main factors. Main factor included four potential threshold of 45 (I1), 55 (I2), 65 (I2) and 75 (I4) centibars for starting irrigation and the sub-main factor included four system pattern as surface (S1) or subsurface (S2) drip irrigation with one lateral for each cropping row (L1) or the alternate laterals (L2). In addition to determining water use and yield, the net return and final discount rate was calculated based on the partial budgeting method using all calcuated costs and benefits. Results showed that the increase in the potential threshold for irrigation decresed the number of irrigation events and the volume of water use. The minimum (136.36) and the maximum (269.11 Mg ha-1) yield was attributed to I4S1L2 and I1S2L1 treatments. Nevertheless, decreasing 11.7% in the volume of water use compared to I1S2L1 treatment, I2S2L1 treatment caused only one percentage reduction in yield and caused the highest net income. Thus, considering both water saving and preserving the economic interest of farmers, applying this method for cropping greenhouse cucumber in Jiroft would be resulted an increase in water use efficiency and final discount rate.

Rainfall-runoff hydrologic models have been recognized as an important and essential tool for water resources management in the world. In this direction, Nash and Hybrid models have been developed as rainfall-runoff models in the recent years. In the present research, the different methods were evaluated to estimate the mentioned models parameters in Alandchay watershed in West Azarbayjan and these models were compared with each other. For this purpose, Hybrid model parameter in the base of empirical method and Nash model parameters using eight different methods were estimated. To evaluate the capability of two mentioned models, the statistical indices such as RMSE, R2 and MAE were used. The less amount of error indices and high values of determination coefficient showed the ability of two models for modeling the flood hydrographs. The comparison of the statistical indices values and calculated errors showed that Nash model had the better performance than Hybrid model. The mean error of peak discharge for Nash and Hybrid modes was obtained 5.99 and 12.07 m3/s and the mean error of flood hydrograph peak time for mentioned models was calculated 0 and 3 hours, respectively.

Root system is effective on increase soil shear strength and slop stability. This study investigates the root system of Tamarix trees on slope of riverbanks indirect flow. Five trees (from TAMARIX species) which grow on the river beech were selected in a distance about one km on SAIMEREH River in Ilam Province. Circle profile trenching method was employed to obtain characteristics. In direct flow, number and diameter of roots was measured on up and down region of plants. Results show that the number of roots on up region is about 11.6 percent more than down region. For all diameters, the number of roots in up region is more than down region. The average of root diameters on up region is bigger than down region. Total root area on up region is about 23 percent more than down region. On up region thick roots contain more percent of total root but on down region it inverse. It is concluded that, indirect flow, root system of riparian trees on riverbank is asymmetrical.

In this research, the impact of macroalgal mats on sediment pattern was studied experimentally. To achieve this object, a series of experiments were conducted in a large flume for different flow conditions and bed covers. The Power Spectral Density (PSD) method was used to separate wave-induced velocities from turbulence. The results showed that the separation of wave-induced orbital velocity from turbulence is possible by using the power spectral density (PSD) method. The sediment results revealed that the bed level variations in bare bed were more severe than in algal bed. So that, the range of its variations in bare bed was three times of algal bed especially in wavy flow conditions. In addition, the average number of ripple crests per meter decreased and the relative ripple wave length increased with increasing of flow discharge. Also the bedload quantity in presence of algae decreased by 80% in unidirectional flow (current) as well as 15% in wave-induced flow (combination of wave and current) conditions.

This study aimed to assess the performance of the conventional methods for estimating soil moisture at field capacity (θfc) and introduce the appropriate PTF under laboratory and field conditions in Khuzestan province soils. The buried probes of the time domain reflectometry device (TDR) inserted at various depths in order to monitor soil moisture conditions in both the physical model and experimental field under a point source drip irrigation with discharge rates of 4 lph. Then, physical soil properties and soil water contents at their specific matric potentials were measured to calculate the hydraulic parameters of Van Genuchten-Mualem model with the RETC program. The results of this research to evaluate the performance of several well-known Point-PTFs showed that the quasi-empirical models based on physical principles can be a good alternative to traditional methods for estimating θfc on the condition that they have been tested in the field. So that, the PTF of Twarakavi et al. (2009) with indices of NRMSE (3.1%) and SE (0.51%) could carefully predict θfc more accurate than the Rosetta (2001) artificial neural network approach which presented the values of NRMSE (5.2%) and SE (0.71%) or the Dexter (2004) equation with the values of NRMSE (9.7%) and SE (1.75%). However, there were not observed any differences in the indicator of model efficiency (ME) for each three PTFs. Based on the assessment results of these PTFs, the negative effects of soil compaction and the amount of sand on the θfc were clearly showed using one-way ANOVA (p

Despite the increase in population and the acute water shortage in recent years, reuse of agricultural waste has been considered as a solution. Due to the presence of contaminants in agricultural waste, attention to environmental issues and their impact on product quality is important. Phosphorus is one of the pollutants from agricultural waste that its unauthorized causes degrading aquatic ecosystems, reducing the quality of water resources and utrification. In the present study, trending of phosphorus removal by limestone and effecting of some factors such as particle size, temperature, pH on phosphorus removal and effecting of hydraulic e of flow on the adsorption isotherm was studied. In this regard, the absorption kinetics experiments on limestone mining Langmuir and Freundlich adsorption isotherm equation based on laboratory scale and physical model of drain channel was performed to investigate the effect of hydraulic flow drainage on the adsorption isotherm. Kinetic experiments showed that the rate of phosphorus removal by limestone was fixed after 30 hours. Two sizes of limestone, there was no significant difference in the percentage of phosphorus removal. Changes lead to a decrease in pH from 2 to 6 percent phosphorus removal was increased from 6 to 11 showed increased removal rate. Optimal pH for phosphorus removal was obtained for alkaline limestone. Increasing the temperature from 22 to 30 ° C was followed by a downward trend of phosphorus removal. Check isotherm, the Freundlich equation by limestone showed good agreement. Statistical comparison of adsorption isotherm and the physical model, the experimental results showed a statistically significant and did not stop.

Accurate estimation of reference evapotranspiration (ETo) is needed for water resources management, farm irrigation scheduling, and environmental assessment. A large number of methods have been developed for assessing ETo from meteorological data. However, most weather stations around the globe are located in nonagricultural setting having dry, bare soil surface and/or concrete surfaces. Using these weather data may cause serious errors. Satellite images cover large cultivated areas and fields. In this study, Penman–Monteith equation converted to a simple equation with three components and for each component presented linear regression with satellite input data. For create and testing regression equations, 297 NOAA- AVHRR satellite images for ten years acquired. The present investigation has been carried out in Amirkabir irrigated unit in Khuzestan province. The results show, simplified equation estimated ETo with a R2 of 0.92 and a error of 8 percent.

The effects of land use change and ploughing method on soil erosion in pastures have been widely known, nevertheless, there is not sufficient information about these human activities in the semi-arid regions, particularly in Iran. Therefore, this study was conducted to investigate the effect of land use change and plough method on surface runoff, soil loss and crop yield in poor vegetation cover pastures, in a semi-arid region, NW Iran, 2014. Four short pastures with 12.6, 15.37, 17 and 19.4% slope steepness were considered in the area and six plots (3m×10m) were installed in each land early autumn 2013. The plots were consisted of pasture vegetation cover, rainfed wheat cultivation up to down slope and rainfed wheat cultivation on the contours. A total of 24 plots were investigated using completely randomized block design at two replicates. Runoff and soil loss were measured at the plots under natural rainfall events during 8 months growth period. Soil loss was also measured at the plots outlets after each natural rainfall event causing runoff during the study period. Significant differences were found between the cultivated plots and pasture plots in runoff and soil loss (p

One way to deal with the water crisis is the use of unconventional waters (such as subsurface waters) with a good crop management. The use of these waters may affect the saturated hydraulic conductivity. But the direct measurement of saturated hydraulic conductivity requires spending a lot of time and cost. A lysimeter experiment was conducted in order to investigate the effect of water table salinity and depth management on saturated hydraulic conductivity and effective porosity and to determine the relation between them. The statistical design was a split-split plot arrangement of a randomized complete block design with three replicates in each treatment. Treatments included 3 levels of groundwater salinity (main plot; S1=

This study examined the adsorption of lead (Pb) ions from aqueous solution onto shrimp shell. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, equilibrium time, and different initial concentration of Pb(II) ions were evaluated. The results indicated that the pseudo-second-order kinetic model could describe the kinetics of Pb adsorption by the adsorbent. With increasing Pb concentrations from 100 to 1000 mgL-1, the amount of Pb adsorbed by shrimp shell increased from 9 mg g-1 to 90.2 mg g-1. Increasing suspension pH from 4 to 7, enhanced adsorption of Pb. Further increase in pH from 7 to 10 resulted in decreasing of adsorption of the metal ion. The average adsorption of Pb by the adsorbent at pH 6 and 7 was more than 95 percent. The Sips and Freundlich models well described the adsorption of Pb isotherms data. Infrared spectrum analysis of adsorbent before and after adsorption of Pb showed that the N atoms of the amine functional groups played a major role in shrimp shell for adsorption of Pb.

This paper presents the results of an experimental program developed to investigate the effect of an additive agent branded CBRPLUS on the mechanical behavior of a forest soil with high plasticity. Various experiments consisting of Atterberg limits, standard compaction, California bearing ratio (CBR), swelling potential and swelling pressure were conducted on natural soil and soil stabilized with various percentages of CBRPLUS. The results indicated that the addition of this material (at the rate of 0.05%), significantly changes the physical and mechanical properties of rehabilitated soil, including, reduction of the liquid limit (at least 6%), plasticity index (at least 9%), swelling potential (at least 27%), and swelling pressure (at least 45%), and also increasing the bearing capacity of soil (at least 53%); hence, the improvement of soil properties is a function of mass percentage of CBRPLUS. Furthermore multiple regression models were developed for CBR, swelling potential and swelling pressure as a function of additive agent percentage, plasticity index and maximum dry unit weight with accuracy and a high degree of agreement between experimental and predicted values. In addition a sensitivity analysis was also performed to investigate the effect of various parameters on CBR, swelling potential and swelling pressure values.

Many analytical methods proposed for solving two-dimensional problems of groundwater are concerned with functions which transform the problem from a geometric status where solution must be found, to another status in which the solutions are known. Conformal mapping and its appropriate techniques allows us to change complex flow problems into regular geometric shapes. In this paper, an analytical solution is provided for calculating uplift pressure in alluvial foundations below dams. In the present study, velocity Hodograph and Schwartz-Christoffel integrals are used to determine the uplift pressure in alluvial foundations in different depths and sizes of sheet pile and upstream blanket. An important point in this study is the asymmetric insertion of blanket relative to sheet pile along the longitudinal path. Finally, the results obtained from this method and the results of laboratory methods were compared to evaluate the accuracy of analytical results and to critically discuss the strengths and weaknesses. The results indicate that in some cases new analytical method underestimates uplift pressure while in some circumstances there is a good agreement between them.

This study was performed to investigate the effect of different levels of irrigation water applied in tape drip irrigation on yield, seed yield components, oil yield, seed oil percent and seed water used efficiency of three sesame varieties in Behbahan agriculture research station for two years 2011 and 2012. The experiment was performed in split plots as a randomized complete block design with 3 replications . The main factor was the different levels of irrigation water (50%, 75%, 100% and 125% water requirement) in tape drip irrigation and sub factors were three sesame varieties including Syntetik, Yellowwhite and Behbahan local variety.The results showed that the effect of different irrigation water amounts on seed yield and its components and the seed water use efficiency was statistically significant at 1% level. The effect of canola variety on seed yield, seed thousand weight, number of capsules per plant and seed water use efficiency was significant at 1% level and the best variety was Behbahan local variety. The highest seed yield was found for the treatments 125% water requirement (1341 Kg/ha) and 100% water requirement (1345 Kg/ha), respectively. However the treatment 100% water requirement was the best treatment as it consumes less water. The water use efficiency in the best treatment (Behbahan local variety with 75% water requirement) was 0.135 Kg/m3.

For sustainable use and vulnerability assessment of aquifers, the groundwater recharge estimation is necessary. In Iran where located in a semi-arid region, the groundwater recharge is closely dependent on the return flow from irrigation. Therefore, determining the proportion of the return flow in recharge from different irrigation methods is essential for better management of groundwater resources. In this study in Neyshabour watershed, the recharge amount of two different irrigation methods (furrow and sprinkle irrigation) were estimated using soil moisture measurement in 2 wells of a wheat farm with 6 meters depth. In each well, the REC sensors were installed with 0.5 meter intervals and two sensors were also installed in 0.15 and 0.3 m depths. Using these sensors, the soil moisture was daily measured during 173 days. Then these values were used to simulate the unsaturated flow in these points using the 1D HYDRUS package. The model in each point was calibrated and implemented to estimate the drainage amount underneath the 6 meter depth soil layers. The drainage amount from 6 meters soil layer during 173 days in the furrow irrigation was 80 mm and in the sprinkle irrigation was negligible.

More than two third of the total areas in Iran has been covered by an arid and semi-arid climate. Although dust storm is an important environmental issue in these regions especially in western and southwestern provinces, limited information is available about characteristics and sources of such phenomena. This study was carried out to identify deposition rate, particle size distribution analysis, heavy metals (Zn, Pb, and Cd) concentrations, and mineralogical composition of dust particles collected using marble dust collector (MDCO) from 15 sampling points in Ahvaz city during a 6 months period in 2011. Results indicated that that the average amount of deposited particles in the periods with dust storms was considerably more than the periods without dust storms. The results illustrated that due to local factors such as the presence of bare lands around the city, and abandoned constructional projects dust deposition rate in such parts was quite more than other localities. Results also indicated that the mineralogical composition of the dust particles is mainly composed of calcite, quartz, and feldspars. Results obtained from particle size distribution analysis showed that the dust particles are mainly silt-sized. However, with occurrence of dust storms the size of particles became smaller. The highest concentration of heavy metals including Pb, Cd and Zn was found in downtown and in neighborhood of industrial regions. In addition, the greatest concentration of heavy metals was observed in December when compared with other months of the period studied.

In this research 110 observed crop yields were correlated with auxiliary variables (DEM and Landsat images) using genetic programming (GP) in Gotvand area (Khuzestan Province). Then, the spatial prediction map of wheat crop yield was calculated using the obtained equation. Wrapper algorithm identified some more important auxiliary variables including NDVI, SAVI, wetness index and channel network based level. RMSE, coefficient of determination and lin's concordance coefficient of GP (1) with all auxiliary data were obtained 525.11, 0.87 and 0.82, respectively. Moreover, results indicated GP (2) with auxiliary data selected by wrapper algorithm could also reasonably predict wheat crop yield (RMSE, coefficient of determination and lin's concordance coefficient, 530.82, 0.86 and 0.79, respectively). It is, therefore, recommended using the same approach to predict spatial distribution of crop yields in the future studies.

Considering high potential of zero-valent iron nanoparticles (NZVI) for contaminants remediation in surface and groundwater, it is important to investigate factors affecting their stability in aquatic environments. In this study, the effects of surface coating and background solution characteristics including nanoparticle concentration, ionic strength, electrolyte type and dissolved organic matter content on the stability of NZVI in aqueous suspensions were investigated. A number of four two-way factorial experiments based on completely randomized design with three replications were conducted to explore the effects of surface coating and each of four background solution characteristics on the stability of NZVI suspension. Initially, bare NZVI (B-NZVI) and Carboxymethyl cellulose coated NZVI (CMC-NZVI) were synthesized and characterized. Thereafter NZVI suspensions were prepared in distilled water at different levels of selected characteristics. The hydrodynamic diameter and zeta potential were then measured in each of prepared suspension. Results indicated CMC-NZVI suspensions were more stable rather than B-NZVI in all tested solutions. Increase in nanoparticle concentration, ionic strength and cation valence of background solution, increased hydrodynamic diameter and decreased zeta potential of NZVI which lead to more aggregation of NZNI and less stability of suspension. On the contrary, increase in dissolved organic matter content resulted in more stability of NZNI suspension. Results also showed that there are significant interactions between nanoparticle type and solution characteristics; as B-NZVI is more sensitive to change in solution chemistry than CMC-NZVI.

In this research the effect of resin on treatment of soil-cement was studied through experimental tests. Three kinds of commercial resins with different weight percent were used in this study. Samples for testing were made of mixtures of soil with different weight percent of cement (8 % and 12%) and mixture of soil-cement with different percent of resin (5, 8 and 10%). Unconfined compression tests were conducted on the prepared samples at different curing times. Results showed that adding resin to soil-cement cause increment in the strength of this mixture. In addition increase in strength is a function of cement percent, resin percent, type of resin (viscosity of resin) and curing time. A regression model was proposed based on the experimental data for predicting the compressive strength. Regression model was consisted of cement percent, resin percent, kind of resin (resin viscosity) and curing time as variables. Comparison between the model predictions and the experimental results shows that the proposed models can satisfactorily predict the compressive strength for the mixture of soil-cement with resin.

In this study, the effects of agronomic, orchard and forest land uses on soil enzymes activities in West Azarbaijan were evaluated. About 75 soil surface samples were collected from studied land usees and soil enzyme activities including acid phosphatase (ACP), alkaline phosphatase (ALP), urease and dehydrogenase were assessed using substrate-reaction methods. Results showed that ALP and ACP activities in the forest land use (344.3 and 582.3 µg pNP/gr.h, respectively) were higher than orchard followed by agronomic. However,urease enzyme in agronomic land use (84.4µg NH4+N/gr.2h) showed higher activity uses which can resulted from high urea application in the agronomic farms. Dehydrosenase activity in the forest (7.2 µg TPF/gr.24h) was significantly higher than agronomic land use. Assessment of soil quality index (SQI) showed ACP and dehydrogrnase, OC, pH, available phosphorous as MDS had the highest effect on studied soils quality among evaluated properties. SQI in forest land use (1.92) was significantly more than orchard (1.71) and agronomic (1.41) land uses. It is calculated that land use has high effect on soil enzyme activity and typically in intact ecosystems (forest) soil enzyme activity is high which can be related to sustanability of these ecosystems.