JWSS - Journal of Water and Soil Science

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Water requirements of paddy fields in the Gilan Province are provided for by a large irrigation network including Sepidrud reservoir dam, Tarik diversion dam, Fumanat network, Sangar diversion dam, and Sangar right and left canals. Because of the deposition of sediments in the Sepidrud reservoir, its capacity has been reduced profoundly. To overcome this problem, sediments are flushed in the second half of each year. The sediments coming from erodible surfaces of the Sepidrud watershed area out flowing from the dam in the spring, and the deposited sediments in the Sepidrud river in the second half of each year are a great hazard for the irrigation network. The objective of this research is to study the effect of the sediments on Sepidrud network. In this research, sediment data from the hydrometric station near Sepidrud dam were analyzed. Sediment samples were collected by a hand sampler (type DH-48) from Tarik and Sangar diversion dams, upper and lower ends of Sangar desilting basin, BP₄ and SP₃ canals, and field ditches and drains. Water discharge was measured by a current meter. Deposited materials in irrigation structures were sampled for grading. The results from this study indicate that the Sepidrud river and Tarik diversion dam deposit sediments at low discharges, but at high river discharges these sediments were found to he erodible. Average efficiencies of left and right desilting basins of Sangar diversion dam were 15.3% and 11.2%, respectively. The area located in Fumanat section, which receives water from Tarik diversion dam, requires desilting structures. The irrigation structures of the network are in danger of sediments. The main and the secondary canals, compared with 3rd and 4th order canals, have less settled sediments in them.

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As unit hydrograph is an important item in flood estimation of the rivers and since flood hydrograph and simultaneous rainfall hyetograph is needed to derive a unit hydrograph, hydrologists recommend synthetic unit hydrographs for areas lacking these hydrometeorological data. A research was conducted in the Zayandehrud-dam watershed (Pelasjan sub-basin) to test the efficiency of synthetic unit hydrographs (Snyder, SCS, and Triangular methods) in hydrological evaluations. For the purposes of this study, natural and synthetic unit hydrographs were determined and compared, using all morphologic, hydrometric and rainfall data. The results showed that Triangular and SCS methods fit natural unit hydrographs better than Snyder method does, but peak instantaneous flow is estimated to be higher than the observed flow. So, the constant 2.083 in peak flow equation is recommended to be changed to 1.74 in this watershed. The Snyder method predicts good peak flows, compared with the other two methods. Generally, it is concluded that Triangular, SCS, and Snyder methods are ranked 1 to 3 for determination of synthetic unit hydrographs in this watershed.

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The interference of biological agents may cause behaviors such as interspecific predation, reducing their efficiencies. The interspecific predation of lacewing, Chrysoperla carnea (Steph.) and ladybeetle, Hippodamia variegata (Goeze) was investigated in the presence and absence of prey, Aphis gossypii Glover under laboratory conditions.

In the presence and absence of prey, the larvae of lacewing fed on eggs, larvae, pupae and adults of ladybeetle and the larvae and adults of ladybeetle fed on eggs and larvae of lacewing. Presence of prey reduced the rate of feeding significantly. Feeding of lacewing larvae on ladybeetle eggs was higher than the feeding of ladybeetle larvae and adults on lacewing eggs. This is probably due to the stalk of lacewing eggs. The 1st larval instar of lacewing was dominant to that of ladybeetle, so were 2nd larval instar of lacewing to the 1st and 2nd larval instars of ladybeetle and 3rd larval instar of lacewing to all larval instars and adults of ladybeetle. Third larval instar of ladybeetle was dominant to the 1st larval instar of lacewing, and 4th larval instar and adult of ladybeetle to the 1st and 2nd larval instars of lacewing. The 2nd and 3rd larval instars of lacewing fed on pupa of ladybeetle but larval feeding of ladybeetle was not observed on lacewing pupa. This was probably related to lacewing pupa covered by a cocoon.

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The efficiency of singular and joint usage of third larval instars of ladybeetle, Hippodamia variegata (Goeze) and green lacewing, Chrysoperla carnea (Steph.) was studied against cotton aphid, Aphis gossypii Glover on cucumber plants in greenhouse.

The predator-prey ratio of 1:30 reduced the population of pest significantly. Singular and joint usage of predators, however, was not significantly different. The predator-prey ratio of 1:90 reduced the population of host significantly but the treatment with larvae of both predators and the treatment with only ladybeetle larvae were not significantly different. However, only the treatment with lacewing larvae was significantly different from the two above-mentioned treatments.

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Any mechanical force exerted on a potato tuber during the harvesting may result in mechanical damage. A few weeks prior to harvesting, haulm destruction could improve the rheological properties of the tuber and reduce its susceptibility to mechanical damage. The effects of elevator and oscillatory sieve diggers and haulm destruction on potato loss and mechanical damage were studied on a farmer field in Fereidan region of Isfahan. Two haulm management treatments (destruction and non-destruction) along with five potato diggers (elevator digger with a long main web and with agitator, elevator digger with primary and secondary webs and with agitator, elevator digger with a main web and with/without agitator, and reciprocating riddle digger) were laid out in a strip block design within a randomized complete block design with four replications. The main crop variety, namely Marfona, was planted in the field.

The results showed that the percentages of undigged and soil-covered tubers were significantly different among the potato diggers tested. These losses were due to the dices located to the sides of shares or gage wheels and wrong adjustments on the diggers. Comparing the performance of reciprocating riddle with elevator diggers, its sieving capacity was low and the severity of the mechanical damage and the numbers of tubers covered with soil were high. Haulm destruction was effective in reducing the peeler type damage (the less than 3 mm deep damage to flesh). Although the elevator digger with a main web (elevator chain) and without agitator had the least mechanical damage index, the differences among the elevator diggers tested were not significant (5%).

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This study was conducted to determine the problems of marketing channels of damask roses and to seek appropriate solutions to enhance marketing efficiency. The results of the study revealed that traditional and industrial rose production lacked the quality demanded by the market. The efficiency index was % 92.9 in traditional and %55 in industrial production. In addition, with regard to the marketing parameters for each type of production, the share of the factors was calculated. So we can conclude that the reducing units have the most important roles in this process. According to the study, traditional units with %47.2 had a greater share compared with the industrial units (%44.5). The results have also shown that production retailer wholesalers and middlemen shares were in the lower ranks respectively. Marketing cost coefficient results showed that %70 of the retailer selling price for 1 kg of the product was related to the marketing costs. The costs for industrial units with high and low capacity were %67.7 and %65.4, respectively.

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One of the simple methods for erosion control, flood mitigation and flood damage reduction in the streams is building the checkdams. The present study was carried out to evaluate the performance of checkdams, location across the streams in the retention of the fine sediments in Droudzan watershed in Southern Iran. For this purpose, a number of streams with many stabilized check dams which were more than 27 years old were selected. For each stream, three check dams (one at the far beginning (upstream), the second one at the middle and the third one at the far downstream) were selected. In each stream, a number of samples were taken from retained sediment behind the selected check dams and also original soil was taken from both sides of the same check dams. Laboratory analysis on the size of particles and also texture of soil and sediment samples showed that in general, soils taken from both sides of the check dams were finer than sediment behind the same check dams. Comparison of particle sizes showed in all streams except Joobkhaleh (with extensive tree coverage) the performance of the third check dams (far downstream) in fine sediment retention is much better than the second one (at the middle) and the second one is more effective than the first one (upstream). Comparison of sands, silt, and clay percentage of soil and sediment also showed that in all streams except Joobkhaleh the clay and silt percentage behind the third check dam is more than the second check dam and that of the second check dam is more than the third one (upstream). In the same way, results showed that the sand retained behind the first check dam, was more than the sand behind the second and first checkdams, respectively. Therefore, if the retention of the fine sediments is the main purpose of the check dam construction, it is recommended that they be built in the far downstream rather than in the upstream of waterways.

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In order to manage the rangeland resources, remote sensing data is able to provide a sensible role of different cases in flora community such as biomass. The study area in SefidAb subbasin of the Lar Dam basin is located in central Alborz, where the climatic condition is semihumid and near to moderate. For the assessment of the sattelite data and their capability in estimation of the range production, Landsat-TM data with different bands was used. In this research, the field data was collected using random-systematic method in 20 sampling units of 200 plots. For geographic coordinates of the sampling units and related pixels in digital data, GPS and also existing benchmark data of the nearest points were used. Then correlation between ground data and vegetation index from different band combination was investigated and the reasonble vegetation indices were obtained. Finally, the best models were extracted for this purpose, which showed sensible relation between the field data and vegetation index. Therefor, it is possible to estimate range production using Landsat TM data related to ground control.

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Overtopping is one of the main factors responsible for dam failure. To avoid overtopping, dam is equipped with one or some spillways to release the water impounded in the reservoir. The number and size of these spillways are determined on the basis of design flood. Determination of design flood of dam spillway can be formulated as a multiobjective risk problem. This problem can be solved by Quantitative Risk Analysis Methods. Here, four economical design methods which are based on risk analysis including, United States National Research Council (NRC), US Civil Engineering, Unit Curve and Partitioned Multiobjective Risk (PMR) were studied. In order to compare these methods, Risk Analysis was performed for re-determining design flood of Pishin Dam Spillway. This Dam has been constructed on the Sarbaz River. Owing to the fact that the integrals of the expected damage relations in the two methods, i.e., Civil Engineering, and Partitioned Multiobjective Risk are analytically unsolvable, Romberg numerical integration technique and Excel software were utilized for the related calculations and drawing graphs. Also, in order to select suitable distribution, the flood analysis was done using Smada software. The findings of the study indicated that design flood determined by the three methods, i.e., Civil Engineering, National Research Council and Unit Curve was almost the same, and that the amount of flood was less than the 10,000-year-old flood while design flood determined by Partitioned Multiobjective Risk Method, was larger than the 10,000- year-old flood.

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In this research, the logging and wood extraction damages caused by wood and paper companies was investigated. The average volume per hectare of compartments 17 and 28 of Waston watershed and Compartment 7 of Alandan watershed was more than 150 cubic meters. So, these compartments were selected as the suitable research sites. The systematic randomized sampling method with 1000 m2 circular plots was used to assess the damages to residual stands and 100 m2 circular plots was used to assess the damages to regeneration. Sampling in skid trail was done with one hundred percent inventory method with a width of 12 meter. Results of this study indicated that 3.2 percent of regeneration was damaged in felling and bucking operations and 4.8 percent of regeneration was also damaged after winching and skidding operations. Most of these damages occurred for thicket stage. The felling and bucking operations damaged 13.6 percent of the residual stand. The amount of damage to the stand after skidding including the whole logging damages equals 15.5 percent. Unnecessary damages to stand and regeneration could have been avoided by selecting the best harvesting method, skidding practices, adequate incentives/disincentives and appropriate supervision.

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Forest future depends on forest stands regeneration. Soil is one of the principal capitals in the forest area. It is important to minimize damages to the forest ecosystem during logging operation. In forestry and forest management, it is significant to know the effect of forest logging damages on regeneration, sapling and soil compaction. This study was carried out in Asalem Beech forest area, in the north of Iran. The forest was harvested by selective cutting method. A systematic and randomized sampling method was used for data collection. Analysis of variance (ANOVA) techniques and binomial distribution were used for data analysis. The results showed 14.5 ± 0.99 percent of regeneration and saplings of forest stands were destroyed and damaged by logging operations with 20 m3/ha intensity per year. 9.12 ± 0.83 percent of saplings were totally destroyed and 5.3 ± 0.63 percent were damaged. These damages were caused due to felling, accumulating, skidding and landing. Soil bulk density in range of 0-10 cm depth, logging and skid trails areas were increased 17.54 and 35.61 percent, respectively. To reduce logging damages and soil compaction in forestry, and manage the forest, we need a suitable organization of timber extraction operation, careful designing and standard construction of skid trails on the basis of logging maps before felling the trees down.

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Reservoir sedimentation is an unavoidable problem which has unsuitable effects on reservoirs such as decreasing of reservoir useful volume, decreasing of dam stability, unsuitable operation of operational gates and penstocks and decreasing of flood control volume. The minimization of reservoir sedimentation is a nonlinear and constrained optimization problem. Constrains imposed include reservoir storage level and releases in each time, and reservoir storage level in the end of operational period. In this study, after calibration of GSTARS3 software, one of the newest mathematical model for simulation of river and reservoir sedimentation developed by USBR, for region of Voshmgir dam, results of running of software were converted as a part of data file to an optimization model by a mediator computer program. After running the optimization model, results were converted to GSTARS3 by another mediator computer program. Then, GSTARS3 was run again with new data file, obtained from running the optimization model. Results of running of GSTARS3 were converted to the optimization model again. The continuation of this process (loop) finished when the desired accuracy was obtained. In other words, the optimum condition was obtained when the running of this loop finished. The constrained optimization problem changed to unconstrained problem using penalty function method. The Powell method, a method of direct search methods, was used to solve this unconstrained optimization problem. Capabilities of the model were demonstrated through its application to the Voshmgir dam in Gorgan for a 12 month period to obtain the optimal operation policy for minimization of reservoir sedimentation.

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Application of drought early warning system is an important strategy for drought management. It is more pronounced in the arid regions where dams have vital role to overcome water shortages. This papers aims to develop and apply such a system that includes three main components, which are 1) drought monitoring, 2) forecasting inflows and water demands and 3) calculation of a warning index for decision about drought management. The system is presented for the Zayanderud Dam. For this, the future six months river inflows and demands are forecasted at different probabilistic levels using the artificial neural networks and considering respected uncertainties. Also, five drought levels are indicated based on the historical records of dam’s storage and the self organizing feature map technique. Furthermore, a drought alert index (DAI) is defined using current storage of dam and the forecasted flows and demands. Finally, the different alert levels are estimated, which vary from normal to sever water scarcity. The results showed that application of the designed warning system can have effective role in the dam’s operation, rationing policy and reducing drought losses.

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In this paper, velocity profiles were analyzed under different conditions such as bed slope, discharge and concentration of density current, and water entrainment. Experiments were carried out in a tilting flume with the density currents being provided using salt and water solution. Results showed that the above mentioned factors have significant effects on the velocity profile characteristics. Dimensionless velocity profiles were also provided and compared for sub-critical, critical and supercritical flow conditions and the results showed that for supper critical conditions the velocity profiles are generally thicker due to the more ambient water entrainment. The coefficients of velocity profile equations were also derived for the jet and wall zones, which showed good agreements with the experimental measurements. Relative values of the velocity profile characteristics were also calculated in order to have a better understanding about the velocity profile structure.

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Investigation in to the sediment delivery of watersheds and its variation is an important element of ecosystem management. Since sediment load depends on runoff quantity, and runoff is considered as a unique indicator of sediment load, in this research the two modified versions of the MUSLE model were evaluated for 9 torrential events in two subwatersheds of the Kamal Saleh watershed in the Markazi Province of Iran. To this end, first all factors of the model including runoff, erodibility, topographic, cover management, and support practice were estimated using routine equations of the model. Then, the power coefficient in the runoff factor was corrected, applying two methods: “m correction coefficient” and “average correction coefficient. The evaluation criteria showed that the “m correction coefficient method” (compared to the “average correction coefficient method”) reduces the difference of the observed and estimated sediment load of small and large torrential events remarkably. In fact, the application of this modified method increased the accuracy of the MUSLE by decreasing the standard deviation of prediction. Also, the validation analysis of the modified method showed that the coefficient of efficiency indexes for the Hasan-Abad station (Rudkhane Bozorg subwatershed) and Ghal'e-No station (Ashur-abad subwateshed) were 0.997 and 0.811, respectively. This result confirms the efficiency of application of “m correction coefficient method”. However, it is suggested that the performance of this method be evaluated using a sufficient number of individual hydrographs and their sedimentgraphs in other watersheds.

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Soil saturated hydraulic conductivity (k) and effective porosity (f) are the most important parameters to simulate the processes associated with irrigation, drainage, hydrology, leaching and other agricultural and hydrological processes. Present methods to measure these parameters are often difficult, time consuming and costly. Therefore, a method which provides more accurate estimates of these parameters is essential and is considered inevitable. The purpose of this study was simultaneous estimation of k and f using approach inverse problem. In this study, analytical drainage model of Glover-Dam was used to simulate the inverse problem method. Also, genetic algorithm was used as an optimization technique for determination of optimal values of k and f. In order to measure the data required for calibration and evaluation of the proposed inverse problem model, a physical model was designed and constructed in the laboratory. The results showed that the proposed method is good for simultaneosly estimating simultaneous soil k and f. Also with variable f assumption, the prediction error of water table around the drainage was reduced significantly.

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Internal erosion is the second major reason for earth dam's failure after overtopping. One of the effective factors in internal erosion in earth dams is the clay minerals used in dams as well as the effects of compaction efforts on soil in sample preparation. In this research, internal erosion and the effect of clay minerals and compaction effort on internal erosion were investigated. For this purpose, Kaolin clay and Na Montmorillonite (Bentonite) separately and with different percentages of mixture were used to investigate the effect of different percentages of Bentonite on internal erosion. Two hammers of standard compaction and modified compaction test were also used to investigate different compaction efforts in internal erosion. The results showed that as compaction effort increased in constant water content, erodibility also increased to about 3%. In addition, it is found that erodibility of kaolin clay is more than bentonite, which reaches 65%. Finally, by adding 12% bentonite to kaolinite, erodibility decreased to a great extent.

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Excess pore water pressure in clay core dams during construction and primary filling reservoir (first impounding) causes initiation and progression of hydraulic fracture. In this research, the instrumentation data during construction and first filling reservoir (first impounding) was analyzed. It measured internal deformations, pore water pressures and total vertical stresses and compared with the analysis results in Masjed-e-Soleiman dam. To do this analysis, GEOSTUDIO 2004 V. 6.02 software was used. The staged construction of the dam was the model in the form of 2D coupled consolidation. The Non-linear elastic model for the core material and Linear Elastic model for other zones were incorporated into the models. For exact assessment and to obtain correct parameters of the constitutive model, the triaxial tests were performed on the core material of Masjed-e-Soleiman Dam and acceptable results were obtained.

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The real estimation of the volume of sediments carried by rivers in water projects is very important. In fact, achieving the most important ways to calculate sediment discharge has been considered as the objective of the most research projects. Among these methods, the machine learning methods such as decision trees model (that are based on the principles of learning) can be presented. Decision tree method is a hierarchical multi step method which is a recursive data collection technique to binary and smaller sub-divisions until the final analysis cannot be divided. Decision trees consider a priori known set of data and derive a decision tree from it. Then, tree can be used as the set of laws to predict unknown features. In this research, the efficiency of this technique for predicting the suspended sediments in Ilam dam basin has been investigated. To evaluate the accuracy of the methods (written by MATLAB software), statistical criteria such as R, BIAS, RMSE, r2 and MAE were computed. The results showed that based on all the statistical criteria, decision tree in comparison with the sediment rating curve had most consistency with the observed data. Meanwhile, the most important factors for creating tree in the model (that had high correlation with sediment data) are the corresponding discharge and daily rainfall.

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Rubber dam body is a lying cylinder that lies in the width of channels, rivers and weir crests and is filled with water or air or a combination of both. Shape of this structure is one of the obvious features that does not change in the path of rivers or dam spillways. Rubber dams may be with or without deflectors. Deflector is a triangular or rectangular fin that is installed down the stream of the dam. The purpose of installing a deflector is separating the water from the rubber dam body and avoiding the reattachment between the water and dam body. In this study, four Physical models of rubber dams and deflectors were made at height and ratio of h/p=0.05 in 2 triangular and rectangular shapes and 25 cm length. Experiments were carried out in three different angles (30-45-60). After all the analyses and experiments were done according to the water napes profile and their lengths, it was observed that the 45 degree is more suitable than 30 and 60 degrees. In addition, experimental data and presented equation in this study were compared with the past equations, the results of which were close, showing the validity of the experiments and equations