مجله تحقیقات آب و خاک ایران
سال چهل و ششم شماره 1 (پیاپی 20، فروردین و اردیبهشت 1394)

A field experiment was conducted with completely randomized block design، three replications and seven treatments for two lasted growth stages of corn. Treatments were: T1 and T2 (50% of T1): full and deficit irrigation with non-saline water، respectively; T3 and T4: variable and fixed full irrigation with saline-non saline water in every other row، respectively; T5 and T6: fixed and variable deficit irrigation with non-saline water in every other rows، respectively and T7: full irrigation with saline water. Irrigation water salinity in non-saline and saline treatment were 8 and 1. 5 dS/m، respectively. The results showed that instead of deficit irrigation with non saline water using alternate furrow irrigation، if not irrigated furrows are irrigated with saline water، are more effective when they are compared with deficit irrigation. In deficit irrigation treatments 29 and 36 % and in T3 and T4 about 50 % of fresh water was saved in 2012 and 2013، respectively. The quantitative comparison have shown a significant reduction in maize yield by 22% with deficit irrigation scenarios (T2، T5 & T6) when compared to salinity treatments (T3 & T4). In terms of water use efficiency، the results indicate that if fresh and saline water are considered as the same worth، deficit irrigation treatments have the highest water productivity and it was not significantly different with T1 treatment. However، water use efficiency is calculated on the basis of fresh water، treatments T3 and T4 are higher water use efficiency than others and، therefore the criteria above have been selected as the preferred option. However، water use efficiency is calculated on the basis of fresh water per treatment، the efficiency of water use in treatments T3 and T4 are higher than others and therefore، they will be selected as the best options.

In the present study، different deficit irrigation management scenarios as alternate furrow irrigations considering sensitive growths stages of corn were assessed in terms of their effects on yield and yield components. This research was performed as a randomized full block design with six treatments and three replications. The treatments were full furrow irrigation in the whole growing season (control)، alternate furrow irrigation in the whole growing season، full irrigation at establishment stage and alternate irrigation in the other stages، full irrigation at flowering stage and alternate irrigation in the other stages، full irrigation at establishment and flowering stage and alternate irrigation in the other stages، full irrigation at flowering and ripening stages and alternate irrigation in the other stages. Overall، the effect of deficit irrigation on yield and yield components was statistically (p<0. 01)، significant. Full irrigation in the whole growing season had the highest wet forage yield (67022 kg/ha) and alternate furrow irrigation in the whole growing season، had the lowest wet forage yield (50064 kg/ha). The best treatment was the full irrigation at flowering stage and alternate irrigation in the other stages. With this treatment، the reduction in wet and dry forage yields، leaves wet and dry weights and stem wet and dry weights in comparison with control was about 8 to 14 %. This is quiet acceptable as it saves 39% irrigation water. The highest irrigation water use efficiency (1. 8 kg/m3) was achieved by full irrigation at flowering stage and alternate irrigation in the other stages.

In order to avoid drought effects، it is essential to detect and monitor the spatial and temporal changes of the phenomenon. Generally، drought indices are used to achieve these goals. The main aim of this paper is to introduce and assess a new drought index named MRDI. The Modified Reconnaissance Drought Index (MRDI) is then compared with the Modified Standardized Precipitation Index (MSPI)، based on the Standardized Precipitation Index (SPI) and the Reconnaissance Drought Index (RDI)، involving well known statistical technique named Principal Component Analysis (PCA) in Gorganroud basin، Iran، as a case study. According to the results، the new MRDI and also MSPI multivariate indices have shown more accurate results and are also easier to use than the SPI and RDI univariant indices. Comparison of MRDI and MSPI results، based on the non-parametric Kolmogorov–Smirnov test in Gorganroud basin، has shown that، there is no significant difference between them and their behaviour is similar in more than 90% of the cases. Evaluation of the latter result needs to repeat this study in more reagent basins.

Drain envelopes have significant roles in performance of drainage systems due to reduce sediments into the drainpipes and also increase the hydraulic conductivity of soil around the drainpipes. In this research، the effect of 1000 hours flow on dual envelopes consist of geotextile as improving the hydraulic gradient and rice husk as bio-sorbent، on the hydraulic and chemical trends under paddy field conditions without rice، was considered. To do so، drainpipe with two different thicknesses of geotextile at depth of 40 cm on a physical model was installed. Then the drain pipe filled using 5 cm thickness of rice husk. Thousand hours flow test under two different water qualities with 0. 7 and 1. 9 dS/m was done and flow of drainage، EC، sodium absorption ratio and pH of drained water was measured. Results showed that the reduction of flow rate of treatments of rice husk & thin geotextile with saline water (RNs)، rice husk & thin geotextile with ordinary water quality (RN)، rice husk & thick geotextile with ordinary water quality (RV) and rice husk & thick geotextile with saline water (RVs) was 44، 94، 21 and 75 percent، respectively. But totally، RN and RNs treatments had maximum and minimum clogging، respectively. Thickness of geotextiles affected on flow rate and chemical trends، and performance of rice husk among all treatments، didn’t perform properly for saline conditions.

In more irrigation systems in our country، pumping stations equipped with fixed speed pump are implemented. These pumps in addition to waste water، consume excessive energy. Providing a method for adjusting the pumps functioning with obligations of operation can improve efficiency of water distribution and also productivity of energy. One of the choice toward this aim، is employing the variable speed pumps which consistent themselves with variable demand of system. In this study، by coding in MATLAB software، design of pumping stations equipped with variable- speed pumps was done for a drip irrigation system. Then regarding to variable demand of discharge and pressure during irrigation season، the designed system was evaluated and compared with some ordinary operation methods based on constant speed pumps. The results show that the utility of variable- speed pumps to supply the pressure head and discharge is definitely acceptable; while the water losses in ordinary pumping stations، depending on the type of station، is 16 to 36 percent.

Shortage of fresh water resources is a major concern all over the world. Availability of water for irrigation is one of the most important factors in arid and semiarid regions، and treated domestic wastewater becomes an important source. Even after treatment، wastewater may contain a great variety of microorganisms that are hazardous for humans and environment. Thereafter the potential transmission of pollution is a principle concern associated with the agricultural use of treated wastewater. Thereafter various irrigation techniques can be used associated with treated wastewater for agriculture. Accordingly، the present study was conducted on Fecal Coliform in the wastewater treatment in laboratory columns، having 30 cm diameter and 60 cm height irrigated using surface (DI) and subsurface drip irrigation systems (SDI). Samples of the effluent and soil solutions were collected from each column after each irrigation events. Results represented that crowd of bacteries increased in both columns. There were no significant difference between crowds of bacteries in the effluent columns of two irrigation systems. It was observed that contamination of 15 cm layer in SDI was lower than DI column.

So far، for the analysis of seepage under hydraulic structures much research has been conducted in the form of numerical models. However، few field and laboratory works have been done to study boiling phenomena for evaluating numerical models. In the present work، a laboratory model was built to simulate seepage and its controlling measures under sheet piles. The model consists of a 2. 2 m long، 0. 8 m deep and 0. 4 m wide flume، in which vertical sheet piles were provided by Perspex sheets. The flume was made of a steel frame and Perspex as well as thick glass sheets. The effect of position and depth of the sheet pile on the seepage flow، exit gradient and uplift pressure have been demonstrated in the form of dimensionless curves. The results indicate that the ratios and with the maximum upstream water level are best possible depths، for both vertical and inclined sheet piles in the depth of the foundation sheet pile. In other words، inclined sheet piles are much more effective in reducing and controlling seepage، uplift pressure and hydraulic gradient than vertical ones.

Expansive soils are considered a worldwide problem as they cause extensive damage to civil engineering structures. An important characteristic of expansive soils is their susceptibility to volume change due to wetting and drying. This paper presets the effect of pore water quality on the swelling and shrinkage behavior of an expansive soil during wetting and drying cycles. 33 soil samples were prepared by static compaction with various pore water qualities consisting of distilled water، sodium chloride (50g/lit) and calcium chloride (250gr/lit). Wetting and drying cycles were conducted on samples in a modified odometer apparatus under the surcharge pressure of 10 kPa using distilled water as the reservoir fluid during wetting. Results indicated that samples prepared with calcium chloride show more swelling potential compared to distilled water and sodium chloride. Furthermore swelling and shrinkage potential، specific volume and dry unit weight for soil samples reach equilibrium after 5 cycles for distilled water and sodium chloride and 3 cycles for calcium chloride.

The study of changes in groundwater resources of Najafabad is an important issue for water resources management، especially after drying of Zayandehrood River. In the present study trend analysis conducted on groundwater level of 33 piezometeric stations located in Najafabad plain during 1374-1391 using Mann-Kendall non-parametric test. The slope of trend line was estimated by the Sen’s estimator method for each time series. Homogeneity of trends was tested using the Van Belle and Hughes method. Results showed that trends of groundwater level for all stations (except stations located out of drainage and irrigation networks) were significant negative. Significant negative trends exhibited for above 52 percent of stations. Results of trend line slopes revealed that in average groundwater level of Najafabad plain declined about 32 cm/year. The strongest decline belonged to Kahriz-sang-jadid station، which declined about 5. 92 m/year. Results of homogeneity of trends showed that trends were homogeneous for months، but it was heterogeneous for stations. Results of trend maps showed that the maximum level of groundwater changes occurred on drainage and irrigation network range. The isopiz maps showed that some stations located on the drainage and irrigation network range had declined about 50 to 100 meters in recent 17-years.

Studying of water and contaminants transport in the vadose zone required determination of soil hydraulic properties. The current study aimed to estimate and analysis the soil hydraulic parameters through inexpensive experiment of Beerkan in six sample points of various soil textural classes، in Asalem region، in Guilan (Iran). Shape and scale parameters of the hydraulic characteristic curves were estimated from particle size distribution analysis and infiltration experiment respectively. Four fitting methods were used and copmaired including BEST-slope (B/s)، BEST-intercept (B/i)، Derivative Linearization (DL) and Cumulative Linearization (CL). Although scale parameters of any sample points were not estimated feasibly and accurately by DL and CL methods but B/s and B/i methods acted as complementary to each other and estimated feasible and accurate values for scale parameters of all six experimental points. The estimated values of sorptivity by B/s and B/i method were not significantly different، but saturated hydraulic conductivity values estimated by B/i was greater than B/s values. Also comparison of these two methods by relative error showed that B/s is more accurate than B/i. It seems that B/i method overestimates saturated hydraulic conductivity. It is recommended therefore to use B/s method for estimating soil hydraulic properties.

Huge amount of drainage water is disposing from operating irrigation and drainage networks in Khuzestan، SW Iran، that needs to manage and/or reuse. One of the low risk methods of reusing drainage water is to use it for land reclamation. To investigate the effects of water quality on desodification of clay soils of this area، leaching experiments were done in 1. 5×1. 5 meter Plots in “Salman Farsi” sugarcane agro industry، South Khuzestan. Leaching with three different water qualities; 2. 61 dS/m (fresh water from Karun River)، 6. 0 and 9. 0 dS/m (mixture of agro industry drainage water and Karun River water) in three treatments; T1، T2 and T3 respectively، and six replications based on complete randomized blocks design were experimented. Rate of desodification were decreased with increasing leaching water salinity. Using drainwater with salinity of 6. 0 dS/m led to increasing dissolved Ca++ and Mg++ in soil after leaching. The SAR of 0-30 cm soil layer that was 84 (meq/lit) 1/2، after application of treatments T1، T2 and T3 decreased to 9، 10 and 18 (meq/lit) 1/2 respectively. So the sodicity problem was solved with leaching by drainage water with salinity of 6. 0 dS/m، and there is no need to use fresh water. The soil pH was not in the basic range neither before nor after leaching.

Quantitative evaluation of the effects of petroleum contaminated soils on soil physical properties is required for optimal soil and water resources management. The objective of this study was to investigate runoff generation in Kerosene and Gas Oil contaminated soils. For this purpose، the variables of runoff commencement، runoff coefficient، variation of runoff duration time and cumulative runoff were determined in contaminated soils. The experimental treatments were consisted of two concenterations of Kerosene and Gas Oil.. The results indicated that Kerosene and Gas Oil contaminated plots had a significant influence in reducing the runoff commencement. So that، the runoff commencement at non-contaminated plot was occurred 128 seconds later than other contaminated plots. However، different type of petroleums with same quantities had no significant influence on the runoff commencement. In addition، the maximum runoff coefficient was obtained at higher concentration of contaminants. The results further indicated that the runoff coefficient in contaminated plots was about 3 to 3. 5 times larger than that of non-contaminated plots. All the contaminated plots had a significant influence in increasing the cumulative runoff compares to non-contaminated plots.

To study the effect of pH and ionic strength on the sorption behavior of cadmium by biosorbents، a batch experiment was conducted with various initial concentration of Cd2+ (0 – 200 mg. L-1) with two biosorbents (sunflower stalks and apple pruning residues) in two pH (4، 8) and two ionic strength (0. 1 and 0. 03 M). Sorption data were fitted to Langmuir، Temkin and Freundlich equations. Results showed that both pH and ionic strength (IS) had significantly effect on Cd sorption. Langmuir maximum mono layer adsorption (qmax) and binding energy value (KL(increased with increasing pH by two biosorbents and sorption coefficients of Freundlich (KF، n) and Temkin (KT، A) showed similar trends as well. But by increasing IS (from 0. 03 to 0. 1 M) all sorption parameters significantly decreased; in the case of sunflower stalks with increasing ionic strength، on average qmax decreased from 8505 to 8150 mg/kg and KL from 0. 14 to 0. 08 L/mg; for apple pruning residues، qmax decreased from 7550 to 7300 mg/kg and KL from 0. 09 to 0. 06 L/mg، respectively.

Soil-cement has been used widely as a base material for constructing many projects، such as pavement of highways and lining of channels and reservoirs. This paper presents the effect of an organic contaminant (Glycerol) on the mechanical behavior and properties of soil and soil-cement mixtures. Soil samples were prepared by static compaction at maximum dry density and optimum moisture content for various percentages of cement and Glycerol and various curing durations. Results indicated that contaminated soil with Glycerol (3%، 6% and 9%) show lower compressive strength compare to natural soil. Furthermore the decrease in compressive strength is seen to be a function of Glycerol percentage. In addition the use of cement (3% and 6%) on natural soil will cause increase in compressive strength، furthermore the increase in the compressive strength of different soil-cement samples were seen to be a function of cement percentages and curing duration. In addition soil-cement mixtures contaminated with 3% of Glycerol show greater compressive strength compare to uncontaminated soil-cement mixture، however the use of higher percentages of Glycerol (6% and 9%) resulted in a noticeable decrease in strength compared to uncontaminated soil-cement mixtures.

After nitrogen، between the essential nutrients، phosphorus is the most important limiting factor in agricultural yield production in the world. There are different methods for assessing the phosphorus status in soil and water. One of the new techniques in this regard is diffusive gradient in thin films (DGT) techniques. This method based on the ion transport in a diffusion layer and its absorption by a resin layer. In manufacturing the gels in DGT، the material used is monopolies and patented. In this study، acrylamide - alyl agarose gel was used as the diffusion layer and ferryhydrite in acrylamide - alyl agarose gel as the resin layer in DGT assembly and the effect of diffusion coefficient in diffusive gel، diffusive gel reactivity، and phosphorus desorption kinetics from resin gel، phosphorus recovery efficiency from the resin gel and DGT performance in soil and water were examined. The results showed that the diffusion coefficient of phosphorus ions in the gel with a 0. 3% of alyl agarose at 25 °C was 8. 2×10-6 cm2/s and decreased with increasing alyl agarose concentrations. Phosphorous recovery efficiency from resin gel measured by 10 ml H2SO4 0. 15 M was almost 100 percent. The measured P using DGT، showed a strong linear correlation (r=0. 98**) with the phosphorus concentration in the examined solution. In this study، an excellent correlation (r=0. 99**) between the P measured by DGT and the available P measured by the traditional Olsen method were observed in three calcareous soils، implying that DGT may be a suitable alternative method for rapid available P measurement in calcareous soils.