Journal of Water and Soil
Year:2011 | Volume:24 | Issue:5|Papers Count:20

In this research we studied the economical effects of rainfed irrigation and 4, 8, 12 and 16 day sprinkler irrigation intervals as well as their effects on water productivity and tea quality. The study was done in Fouman tea research station, northern part of Iran where tea is a major crop, during growing season of 2002-2004. The results showed that during dry season of 2002 and 2003 yield quality traits e.g. water soluble solid materials and polyphenols of made tea and dry mater of green leaf and water productivity were decreased with increasing in irrigation interval. Mean comparison test showed that 4, 8, 12 and 16 day irrigation intervals raised the yield by 74.5, 71.5, 67.4, and 59.4 present comparing to the rainfed treatment, respectively. Economical evaluation of different irrigation regime showed that the mean benefit/cost ratio for 4, 8, 12 and 16 days and control were 2,1.74, 1.64, 1.43 and 1.5, respectively. Although lower interval caused in cost increasing, higher quality of the situation resulted a higher amount of income. In years with moderate rain it is recommended to increase the irrigation interval.

Rockfill dams are usually used for affecting the flood and reducing the peak discharge. The materials used in these dams will usually make the flow turbulent, therefore Darcy's law can not be used for this kind of dams and the equations based on the non-Darcy flow must be applied. Non-Darcy flow equations are showed in two general ways including:i=aVN and i=rV+sV2 .One of the main parameters for flow simulationthrough this type of media is N, which can be specified empirically using experimental data. N is a parameter for flow turbulence and varies from 1 (laminar flow) to 2 (fully turbulent flow). One of the problems with some of non-Darcy equations (e.g. Ergun) is that they can not compute α and N directly. In this research using the Ergun equation and mathematical analysis, a few equations have been derived and presented for computing N and α and finally a new equation has been presented for the equivalent hydraulic conductivity (Ke) coefficients in porous media. A standard example was used for the verification of the resulting equations. Some values were assumed for the soil properties and the value of N, a were computed using the proposed equations in this research study. N was also specified using a non-linear regression analysis and was compared with the corresponding values obtained from the proposed equations. Comparison of the both sets of results showed that the computed N values are relatively precise especially for the boundaries (N=1 and 2).

Accurate water measurement and delivery are basic issues in irrigation networks management and performance. In this regard, baffle modules have been considered as appropriate means for delivering almost constant discharge within a specific range of upstream water variation. The structure is meant for low discharge delivery and could be employed in farm irrigation. However, the design criteria still requires further improvements. In this paper, the hydraulic sensitivity concept was used to provide two design methods for a 2 baffles module. The results of the first method presented a structure with -13.62% deviation of design discharge.While the second method resulted in a design criteria for baffle sluice module with only 2 baffles which its performance is similar to a 3 baffles one.

Consistent decreasing and increasing of temperature in the short-term period that is called freezing and thaw cycles is one of the important factors of damage to crop productions. In this research as to determine freezing and thaw cycles in the Khorasan Razavi province, the data of daily minimum and maximum temperatures of 9 synoptic stations was used over 20 statistic years (1989-2008). Also 6 distinct range of temperatures including:the minimum temperatures lesser and equal whit -2 and the maximum temperatures greater and equal whit 2 (A), the minimum temperatures lesser and equal whit -3 and the maximum temperatures greater and equal whit 3 (B), the minimum temperatures lesser and equal whit -5 and the maximum temperatures greater and equal whit 5 (C), the minimum temperatures equal whit -2 and the maximum temperatures greater than 2 (D), the minimum temperatures equal whit -3 and the maximum temperatures greater than 3 (E) and the minimum temperatures equal whit -5 and the maximum temperatures greater than 5 were presented. After data processing by a computer program into the FORTRAN space, the number of days with this phenomenon for each station was determinate as monthly, seasonal and annual and then the mapping plans of susceptible areas were prepared. The results show that winter has a higher rate of this phenomenon and autumn and spring are next respectively. Also the investigation of mapping plans indicated that in most temperature ranges, the Torbat heydariye, Nishaboor and Ghuchan stations had maximum number of freezing and thaw cycles in Khorasan Razavi province. The minimum rate of this phenomenon was in the Sarakhs, Kashmar and Sabzevar Stations as well.

Optimal management of water and nutrient could consider as effective on farm method to reduce pollution because agriculture is none point pollution. In this research, an optimal model was presented to reduce nitrate loss in furrow fertigation. The optimal model contains four simulation models for predicting runoff, deep percolation, nitrate concentration in runoff and nitrate concentration in deep percolation. Genetic algorithm was used for model solution. Decided values were inlet discharge, cutoff time of irrigation, starting time and duration of fertigation. Simulation model’s ability to simulate fertigation event cause a comprehensive optimal model of fertigation in different climate, plant, irrigation and fertigation situations. Field experiment of furrow irrigation under continues regime was used to evaluate optimal model. Optimal decided values for inlet discharge, cutoff time of irrigation, starting time and duration of fertigation was determined 0.184 L/s, 595.2 min, 7.5 min and 162.9 min in plant conditions. These values were 0.21 L/s, 537.1 min, 6.5 min and 143 min in none plant condition. Optimal decided values cause 113.86 and 118.3 mg/L mean nitrate loss from farm as runoff and deep percolation under plant and none plant conditions, respectively. Optimal model was increased nitrate concentration in deep percolation or decreased nitrate concentration in runoff by increasing inlet discharge because plant increase nitrate concentration in deep percolation. Results show plant has effect on optimization then it is appropriate to determine optimal decided values under plant and none plant conditions.

The goal of this survey is to prepare the dry land wheat atlas for Zanjan province, according to the climate data. So we can recognize which areas are susceptible and to understand climate capabilities and limitations for dry land wheat. For reaching this purpose first raining and temperature datas of the research region were gathered and analyzed. At the first stage, proper according to the first rain after Mehr which should have continued for 1 or 2 days and rained 5mm or more planting date was defined. Then the different levels of dry planting wheat’s growth were calculated by the GDD method. At the next stage the annual, autumn, spring and Khordad's rainfall were reviewed and the average was calculated. The probability of germination temperatures, maximum temperature 25 and 30 degrees centigrade in the flowering stage and grain filling stage was also calculated. The calculated quantities in the GIS system were converted into different arenas and by using the overlap method all layers were first given a weighing value and were incorporated afterwards. Finally Zanjan Provinces Dry Land Wheat Atlas area with 4zones: very good, good, average and poor was prepared. As you can see in the map the most suitable regions for dry land wheat are in the center and north of Khodabandeh and east of Ijrood and of coarse the other parts of Zanjan province are suitable. At the end the product producing scale is calculated and according to the neighbor provinces turnover scale which have the same weather and a higher turnover, the medium turnover and producing scale for Zanjan was calculated which showed a 30% increase from the real production rate.

The Muskingum method is frequently used to route floods in Hydrology. However, application of the model is still difficult because of the parameter estimation’s. Recently, some of heuristic methods have been used in order to estimate the nonlinear Muskingum model. This paper presents a efficient heuristic algorithm, Simulated Annealing, which has been used to estimate the three parameters nonlinear Muskingum model. The results show the high accuracy of the algorithm in estimation of the parameters, so that it is obtained terms of the sum of the square of the deviations between the observed and routed outflows (SSQ), the sum of the absolute value of the deviations between the observed and routed outflows (SAD), deviations of peak of routed and actual flows (DPO), and deviations of peak time of routed and actual outflow (DPOT), 36.78, 23.44, 0.9 and 0, respectively.As Value of the SSQ has obtained equal its value Harmony Search method that is the best answer between the heuristic Optimization Algorithms that has been used so far. Finally, the performance of the new proposed method has been compared with other methods. The results showed that the height efficiency of the algorithm in parameter optimization of the nonlinear Muskingum model. SA algorithm in the second example the Karun River flood test and the results were compared with the GA method. The results showed that SA algorithms estimate is better than the GA method. As the error sum of squares (SSQ) before 4947/06, the total absolute error (SAD) against 412.8, Dubai actual peak was 1182 cubic meters per second and peak Routing 1191 was obtained by the difference of these two (DPO) times less a percentage error and the occurrence of different steps in Dubai when the real peak and has Routing (DPOT) zero respectively. Finally, this research capability in the blank verses optimal SA algorithm making Muskingum model parameters indicated therefore, to use SA algorithm in this area is recommended.

Development of greenhouse gases in future periods not only causes change in average amounts of climate variables but also makes variables of this variability affected. Then for sure concerning alternations followed with climate variables’ fluctuations and its average amounts in effecting on runoff would make more reliable results. In this inquiry initially fluctuations and average amounts of climate variables of Gharesuo basin were simulated by HadCM3-A2 model and Statistical Downscaling method in 2040-2069 periods. Although to mention climate fluctuation’s uncertainty in calculations, they acted to simulate 100 time series of temperature and precipitation variables for future period. Results showed that uncertainty confine of region’s climate fluctuations has increased 0.5 to 2oC in temperature and 10 to 20mm changing in precipitation in different months of year. After that and to mention Hydrology model’s uncertainty, two rainfall-runoff models of SIMHYD and IHACRES are used. These two models calibration for base period and introducing 100 time series of climate variables produced in last level into both models specified the basin runoff’s changing confine for 2040-2069 period. Results declare the coordination of two models in region’s runoff changes. As both models estimate runoff abatement for fall season and enlargement for other seasons. Finally the results of this inquiry estate the effect of hydrology model’s uncertainty and less effect of climate variability in estimat ing a basin’s runoff under impact of climate change.

Guilan is a famous province in growing rice in Iran. Recently, due to shortage of water, farmers' desire to use groundwater in order to grow rice in northern part of Iran has been increasing rapidly. The fact that rice is sensitive to water quality, caused concern about rice cultivation sustainability in the area, especially in drought years. This study was done to investigate the spatial variability of some important ground water quality factors including EC, SAR and Na of samples taken from 135 wells over the region during the summer of 2007. First, the accuracy of Kriging (Ok) and Inverse Distance Weighting (IDW) with 3 different powers (1, 2 and 3) in mapping the studied parameters were evaluated. Then the final map was presented. The result showed that spherical model gave the best result to simulate the Vriograms. Although negligible difference was observed between the methods, Ok and IDW1 performed better in comparison to the IDW2 and IDW3. The final map showed that Ec in central part of the region, where the Sepidrod River meets the Caspian Sea is dramatically high which will threaten the sustainability of rice cultivation in the area. The other factors were in suitable level.

One of the major factors on the amount of water resources is river flow which is so dependent to the hydrologic and meteorologic phenomena. Simulation and forecasting of river flow makes the decision maker capable to effectively manage the water resources projects. So, simulation and forecasting models such as artificial neural networks (ANNs) are commonly used for simulation and predicting the exact value of such factors. In this research, the Dez River basin was selected as the case study. This paper investigates the effectiveness of temperature, precipitation and inflow factors and the lag time of those factors in inflow simulation and forecasting. Genetic algorithm (GA) has been thus used as an optimization tool, determining the optimum composition of the effective variables. Thus, in a flow simulation and forecasting model, the number of hidden layers, effective neurons in each layer, effective meteorologic and hydrologic parameters and also the lag time of each factor of flow simulation and forecasting has been considered as decision variables, and GA has been used to obtain the best combination of those variables. In this study, minimization of the total mean square error (MSE) has been considered as the objective function. Results show GA's effectiveness in flow simulation and forecasting with consistent accuracy. The value of R2 criterion has been obtained 0.86 and 0.79 in the simulation and forecasting models, respectively. The results also showed superiority replies obtained from the simulation model to the prediction model. One of the reasons for this superiority can be considering the meteorological factors in the current month in river flow simulation.

Wenner direct contact method is a method of estimating apparent electrical conductivity (ECa) of agricultural soils in situ. This method can be affected by factors such as quality of electrodes in contact with soil, type of employed electric current, moisture content, clay content and compaction of soil. In this research, the effect of electrode type (rod and plate) and electric current type (direct and alternating) on accuracy of estimating soil ECa has been investigated to design a soil EC mapper. A prototype soil EC meter based on direct contact method has been made. The device assessed by a completely randomized experimental design with factorial layout. The independent variables were soil salinity (five levels), electrodes type (two levels) and current type (two levels).Four soil types with different clay contents from regions around Mashhad city (Khorasan Razavi, Iran) have been used with three replications. The results analyzed with SPSS17 software and validated with 1:1 soils water extract EC’s. Significant difference between electrodes types and electric current types was observed. The correlation coefficients of direct contact measured EC’s with soil water extract EC’s was between 0.94 and 0.99 for all treatments. Based on the results of this research, plate type electrodes and AC current were recommended for the design of tractor rear mounted soil EC mapper.

Many studies have been conducted on the characteristics of hydraulic jump over gradually expanding cross sections, but comparatively few have been carried out on basins with convergent wall. In the present research, the hydraulic jump characteristic of the stilling basin with convergent wall has been investigated. The main objective of this research is evaluation of conjugate depths ratio, jump length and evaluation of hydraulic jump energy loss. According to the charts and results of this study, which are based on measured data, conjugate depth ratio decreases 56 % compared with the vertical case. Also, convergence of the walls along is decreased by 51% of the jump length compared with the classic jump.

Nowadays, fuzzy technique is used to prepare the map in different sciences, extensively. With due attention to important role of soil fertility in modern agriculture, the preparation of soil fertility map seems to be necessary to plan for appropriate using of fertilizers for crops. This study was conducted to prepare a distinct map for evaluating soil fertility according to soil available K and P, and soil organic matter factors in Shavor region in Khuzestan province. The fuzzy technique and the Analytic Hierarchy Process (AHP) were used for mapping soil fertility into Geographic Information System (GIS). For this, the amount of soil organic matter, and available soil phosphorus and potassium obtained form 282 profiles of soil, as the input data, were used. In the first stage the interpolation of data was done by Inverse Distance Weighting (IDW) model into GIS. Then a membership functions was defined for each factor. Finally, the map of soil fertility was prepared by using AHP technique into program of Expert Choice with adjustment rate of 0.05. Results showed that 51, 26, 12 and 11 percentage of lands were classified base on soil fertility into groups of very weak, weak, moderate and suitable, respectively.As a final result, this types of distinct soil fertility map can able us to manage the appropriate using of fertilizer.

Lateral intake is a hydraulic structure which is used for diversion of some portion of water from a river for the purpose of irrigation, storage and industrial. Most of lateral intakes from canal are installed at canal with inclined banks which has not received the attention of the researchers in the past. Since the flow discharge and sediment which enters the intake canal depends on the flow patterns at the head of the intake and the inclined banks can affect the flow patterns and so the sediments, this study has been conducted. In this study a series of experimental tests are conducted using canal of vertical bank and a series of tests with canal of inclined banks. In all tests the suspended sediment feed with a constant concentration upstream of the intake. Sediments which enter the intake canal were collected after each test and weighted. Using dimensional analysis a general nondimensional relation was developed. By applying the experimental data it was found that the flow patterns at the upstream of the intake has been modified in such a way that more water from surface layers are diverted.Therefore less suspended sediment enters the intake. Also it was found that in all tests the amount of sediment enters the intake reaches its minimum value at Froude number equal 0.37. In low flow depth because of the effect of bed roughness, the suspended sediment enters the intake is higher compare to the higher flow depth for the same conditions.

In this study, the effect of suspended load transport on the characteristics of submerged hydraulic jump (SHJ) in a rectangular channel was investigated experimentally. Sediment concentration and jet Froude numbers in the range of 0.424%-16.15% and 1.93-4.96, respectively, were considered. Tow grain size 0.15 and 0.03 mm were used in the experiments. Characteristics of submerged hydraulic jump including velocity and concentration distribution, length of jump, the submergence depth on the gate and the energy dissipation were studied. The results showed that the submergence depth on the gate and the energy dissipation are constant by increasing of sediment concentration. The length of the jump at the presence of suspended sediment is smaller than those due to clear water flow. Also, suspended sediment by decreasing of flow resistance is made to decrease flow velocity.

Using mathematical models for irrigation management have great impacts to increase irrigation efficiency and product amount, in fields. In this study, simulation results by SWAP model for moisture, compared with soil profiles moisture values, measured in the field. Moisture data, measured at three wheat farms in the Neyshabur plain, were used to predict moisture. Results show good agreement between simulated and measured moisture values. R2 coefficient values were 0.611 for Farob Roman farm, 0.648 for Haji Abad farm and 0.679 for Soleimani farm, respectively. Model absolute value was between 1.5 to 2.9 percent and root mean square error (RMSE) value was between 1.9 to 4 percent. According to these statistical indices, SWAP model has been able to simulate moisture, in soil profile in different depths and times, accurately. Therefore, SWAP can be used for irrigation management in Neyshabur plain, with relatively sufficient accuracy.

The grasses cold tolerance is the most important limiting factor for its cultivation in temperate regions, so using cold tolerant cultivars is essential for grasses successful cultivation. In order to evaluation freezing stress tolerance of several species of grasses, this study was conducted in Agricultural faculty of Ferdowsi University of Mashhad as a factorial complete randomized block design with three replications. Experimental factors included six types of grasses and 14 freezing temperatures. To assess grasses cold tolerance, electrolyte leakage test and LT50 for leaf and crown tissues was used. The results showed that reduction of freezing temperature, increased electrolyte leakage percent from leaf and crown tissues and difference between the grasses was significant. The effect of freezing temperatures on electrolyte leakage from leaf tissue was higher than the crown. Maximum level of electrolyte leakage from leaf tissue (at -16.5 oC) was 90 percent, while the maximum leakage from crown tissue (at -18 oC) was 76 percent. Based on leaf LT50, ecotype Mahalat and Bermudagrass were the most cold sensitive and Starlet and ecotype Yarand were the most cold tolerant grasses.The crown electrolyte leakage and LT50 were different between grasses significantly. Accordingly, crown electrolyte leakage percent was minimum for Starlet and maximum for Mahalat and crown LT50 index was minimum for Mahalat and maximum for Yarand.

Different definitions have been proposed for soil quality. Various soil properties have been suggested as soil quality indices by researchers. This research was conducted to study the relationship between slope of retention curve at its inflection point (S index) and other soil physical quality indices, because the researches between S index and soil physical properties are little. Thirty five soil samples were collected and some physical and chemical properties measured. The moisture contents were measured at 0, 1.5, 2.5, 5.5, 10, 20, 30, 50, 100, 200, 300, 500, 1000 kpa pressure heads. The parameters of Van Genuchten equation (1980) were determined by using of RETC software. The slope of retention curve at the inflection point was determined and it was considered as soil physical quality index (S). Then the relationship between S index and soil physical properties was determined by SPSS software. According to the S index and penetration resistance (PR), it seems that the physical quality of studied soil samples was suitable for accessing. Also there was a significant correlation between S index with mean weight diameter (MWD), clay percentage, sodium absorption ratio (SAR), organic matter percentage, electrical conductivity (EC), least limiting water range (LLWR), available water content (AWC), and penetration resistance (p<0.01). In addition the correlation between S index with bulk density and calcium carbonate was significant at p<0.05. Among the studied parameters, the correlation between S index with clay percentage, bulk density, EC, and penetration resistance was negative and S index had a direct relation with other soil properties.

Drastic Precipitations in unmorally times always are one of the important factors that created abundant damages in different geographical areas. In this research, three Precipitations that occurred in summer 2009 in Mashhad were investigated. The investigation of variation graphs of meteorological parameters show significant decreasing of air pressure and temperature and increasing of relative humidity and dew point in days of occurrence precipitation compare with previous days. The result of physical analysis by using thephigram showed that existent of thick cloud whit noticeable perceptible water in sky of local in days of occurrence precipitation. Also situation of LCL and FCL levels and difference of height between top of cloud whit FCL and amount of dynamical indexes of CAPE, SHOW and KINX explains noticeable potential energy of ascendable air mass and suitable conditions for drastic instability of weather. For example amounts of dynamical indexes for torrent day (15 Sep) obtained 953.4, -4.67 and 35.30 respectively that are demonstrator of hard instability in this day. The investigation of surface isobars map showed contrast of tow Low and High pressure systems in east of country. Also 850 hpa isobars map indicate advection of warm weather from south to northeast that is similar whit surface pressure patterns. Therefore prove that developing of Siberian High pressure in warm season synchronic whit advection of warm and humid weather from south that caused drastic instability suddenly and this subject is supported physical analysis of vertical profile of atmosphere.