فصلنامه علوم و مهندسی آبیاری
سال چهلم شماره 1 (بهار 1396)

One of the most important information which is effective in desirable utilization of water resources is the information related to predicting the future available water in the catchment. Considering the existing uncertainty it is of significant importance when streamflow forecasting information is used. The ensemble stream flow prediction (ESP) is one of the methods in considering the forecast uncertainty. The goal of this research is to develop and evaluate monthly ESP for Roud Zard basin in Iran. Two models have been used to produce ESP: A conceptual river flow model based on Tank method (CRFM)¡ and Combining the CRFM model with the adaptive neuro fuzzy inference system (ANFIS) to develop a hybrid model. Following¡ the Event bias correction method is employed on generated ESP’s and the results of the three predictions have been evaluated. The results show that the precision of base stream flow simulation model had considerable effects in the quality of the ensemble prediction as far as RPS in hybrid model that had higher precision than CRFM model has decreased from 0.56 to 0.38 and the months with suitable prediction (positive skills score) increased from 82 to 115 months and in case of employing bias correction¡ there will be an increase to 119 months from the total 182 months of simulation period.

The aim of this research is to develop relations to estimate the flow resistance coefficients in gravel-bed channels. In this regards, the experiments were carried out in a tilting flume with length of 8m and width of 0.25m. In this research, four different bed slopes (0.004, 0.006, 0.008 and 0.01), two gravel types (natural and crushed shapes), three mean diameter (d50) of gravels (65.3, 46.6 and 38 mm) and four discharges (0.01, 0.017, 0.024 and .031 m3/s) were used as a variables. New flow resistance equations were developed for natural and crushed gravels by using the new definitions for dimensionless variables in terms of non-dimensional hydraulic geometry equations. Also, new equations were presented to estimate Manning’s roughness coefficient for both shapes. In addition, the results showed that the developed equations based on non-dimensional hydraulic geometry relations are the best way to link the mean flow velocity to the flow discharge in mountain rivers.

Vortex is created when flow possed a group of obstacles such as bridges piers, docks and etc. Transverse wave is created by overlapping the vortex that created behind obstacles and due to adapting of the vortexes frequency with natural frequency, of channel dimension. All experiments in this study are done on a flume with 6m in length, 0.72m in wide and 0.6m in height. As obstacles in the flow were, wooden cubic obstacles. The discharge of flow was equal to 20 lit/s and the regime of flow was sub-critical. In all arrangements by reducing the height of submerged obstacles and increasing their submergence ratio, gradually wave amplitude of type 1 and type2 is reduced and the maximum amplitude was also reduce until it completely disappears. For example, in test No. 1 with 21% submergence any wave was not observed. also the maximum amplitude in the non-submerged situation was more than the submerged sitoation.For example, in test No. 1 the maximum amplitude of wave is type 1 was 4.3 mm, This value reduced to zero in the submerged situation. Finally a relationship is proposed to estimate of amplitude of transverse waves for submerged case.

Increase in water consumption due to population increase, is reduced the quality and quantity of extractive water. Management of water resources specially groundwater in arid and semi-arid areas are very importance. Jiroft is one of the most important agricultural areas in Iran which in recent years, because of irregular exploiting of groundwater has faced severe downfall of the water level. Therefore, in this research the groundwater levels and rainfall during 2014-2017 to evaluate exploitation of groundwater resources and the possibility of feeding them by the precipitation in Jiroft were studied. For this purpose, the Artificial Neural Networks (ANN) model was used. Results showed that with current trends of groundwater exploitation, the levels of them over the next 4.5 years will reduce to about 6.68 meters and precipitation with current trends groundwaters exploitation can not help to increase the level of these waters in this city. Therefore, strategies such as raising water productivity in agriculture and the use of modern methods of irrigation, to reduce water consumption and thereby prevent further exploitation and reduce the level of groundwaters can be used.

Wind causes temperature and humidity displacement and also increases evaporation rate. Geostatistical methods because of theirs high accuracy in local estimation of geographical parameters and capability on reducing sampling number are suitable methods to determine the spatial interpolation of hydro-meteorological parameters such as wind speed. In this study, firstly, geostatistical interpolation methods were compared to estimate wind speed. Secondly different parts of Khozestan province were classified based on the wind speed, using cluster analysis. Finally, squared Euclidean Distance method was applied to determine the degree of similarity of stations. And also, Ward method was used for merging the stations. The results indicated that the maximum wind velocity occurred in the southern areas during cold months of the year and speed of wind in the northern parts of the study area was less than the other parts all over the year. Furthermore, 9 wind speed maps were developed based on stations cluster classification. The results of this research can be applied in order to identify the suitable places for sprinkle irrigation usage.

Vertical drains installation can be used to accelerate the consolidation settlement. In this research, three dimension equation of consolidation in cylindrical coordinate with certain boundary condition was obtained and the analytical solution was performed. Then, the results at the MATLAB were written and the variation of degree of the settlement versus time was investigated. The results with experimental data of odoemeter test were also compared. The account of radial drains in this model were considered 0.5, 1, 1.5 and 2 cm. To verify the analytical solution, in the isotropic soils and zero radius of the vertical drain, the results and the traditional Terzaghi’s method were fully established with suitable satisfactory. The results showed. The most difference of 100% settlement velocity between of Terzaghi method and radial-vertical method was related to 40kg loads at the drain’s with 2 cm radius. This amount was 6 hr, however, the least of difference time of 100% settlement velocity was related to 5 kg loads at the drains with 0.5 cm radius and this time is 1 hr. However, results showed the analytical solution in comparison to numerical methods are predicted less time of average degree of consolidation as more accuracy.

Since the starting time of cotton irrigation has a considerable effect on the net income of cotton ‘s farmers, therefore, this research was conducted in Hashem- Abad Cotton Research Station, during 2007-2011 years, on Golestan variety and six initial irrigation treatments including: one week before the start of squaring stage (I1), early squaring stage (I2), early flowering (I3 ), one week after flowering (I4), two weeks after flowering (I5) and irrigation three weeks after flowering (I6) in a randomized complete block design with three replications. Sowing was done with the seed planter. The amount of irrigation water was calculated based on the soil moisture defficit. Other agricultural operations including Weed control, thinning and pest control were done under the supervision of experts.Three plants were randomly selected from each treatment and yield components were recorded on them. Results showed that the effect of initial irrigation treatments on yield, earliness, boll weight and lint perecentage was significant at the level of one percent, So that, by delay in starting irrigation, these parameters were decreased. The highest seed cotton yield, with 3951 kg/ha and 3594 kg/ha was obtained in I2 and I1 treatment, respectively. But in terms of water use efficiency, it is recommended to start irrigation at one week after flowering stage.

This study was conducted to evaluate the effects of different levels of irrigation water and potassium fertilizer on the yield and its components of sorghum forage. This research was carried out in the Agricultural Research Center of Semnan (Shahrood) in 2014. The factors in this study were the irrigation water in three levels (50, 75 and 100% water requirement) and potassium fertilizers in three levels (0, 50 and 100% of the required fertilizer based on soil test) and forage sorghum varieties (Pegah, Karaj and Speed feed). The analysis of variance of data showed that the factors of water and potassium fertilizer on yield, shoot dry weight, plant height, number of leaves per plant, leaf dry weight, leaf area and stem dry weight were significant (1%). The highest forage yield was obtained from the 100 percentage level of the water and fertilizer. The efficiency of water use in water level of 75 percent was more than other levels. The highest yield was observed from W100K100 treatment. Thus W75K100Vp treatment was recommended as a superior treatment. To determine the functions of forage yield - water - potassium fertilizer, linear, logarithmic linear, quadratic and exponential mathematical equations were used. The Quadratic equation was chosen as the premier equation. In order to study the separate and combined effects of irrigation water and potassium fertilizer on the yield forage sorghum, the marginal production (MP) and the rate of substitution (MRTS) for irrigation water and potassium fertilizers were calculated. The marginal production of water irrigation (MPI) and marginal production of potash fertilizers (MPK) were equal to 1.52 tons per cm and 0.076 (ton/ kg. ha), respectively. The rate of technical substitution of potassium fertilizer instead of irrigation water (MRTS) for forage yield was determined as 0.05 kg. The average monetary value of forage and final production of potassium fertilizers were obtained as 3040000 and 152000 rials respectively.

In order to evaluate the effect of different crop management methods and irrigation with saline water on evapotranspiration and water use efficiency of Maize, the factorial experiment with randomized complete block design was conducted. This project was carried out in the Agricultural farm of Shahid Chamran University of Ahvaz from March to June 2015. Different crop managements include without crop residues, use of crop residues on soil surface as mulch and mix of crop residues with surface soil layer to 30 cm depth and water irrigation salinity include water salinity of Karoun river (2dS/m), 4.5 and 7 dS/m. The results of variance analysis showed that the effect of salinity, crop management and their interaction effect on evapotranspiration, yield and water use efficiency was significant. Minimum values of ET (387.5mm) and WUE (0.68 kg/m3) were obtained at the salinity level of 7 dS/m. The management of residues use as mulch had the most effect on ET decrease (9%) and yield increase (10%) and So, the maximum WUE (1.10 kg/m3) was obtained at it too. The greatest impact of residues applications mulch and mixing with soil surface layer in increasing of yield (19% and 9% respectively) and WUE (27.6% and 10.6%, respectively) compared to non-use of residues was observed at the salinity level of 4.5 dS/m. Therefore, the use of crop residues particularly as mulch can be recommended as an effective way to reduce the damage of irrigation with saline water.

One of the methods for a local scour countermeasure at bridge piers is the use of submerged vanes. Vanes change the regime of bed load movement that led to control place of deposition and erosion. In this paper the effects of submerged vanes with different forms flat, curved and angled in number (2 and 6) and various configurations (the distance D and located on the pier symmetrically with respect to the flow line) on reducing local scour around cylindrical pier with angle of 20° was performed to investigate. Experiments were conducted in a 10 m long and 0.3 m wide flume and a cylindrical pier of 2.54 cm diameter. Clear-water scour tests with u*/u*c=0.92 were performed. The length of the vanes was equal the pier width and was installed on the bed. Results showed that reduction of scour with different arrays of six vanes was 93%. The highest reduction in scour depth was achieved for curved vanes are placed around the pier.

In recent years, metal contamination in the aquatic environment has attracted global attention owing to its environmental toxicity, abundance and persistence. This study was carried out to determine the concentration, origin and toxicity of heavy metals (Fe,Mn,As,Ni,Pb,Zn,Cu,Cr) in surface sediments of Bahmanshir River.14 surface sediment samples (0-10 cm) were collected using a grab sampler. Concentration of heavy metals was measured using ICP-OES method. Physico-chemical parameters (pH, Organic Matter (OM)) of sediment were determined by standard methods. In order to assess sediment contamination to heavy metals, different indices, Enrichment Factor, Potential acute toxicity and Ecological risk were calculated. The results showed moderate contamination of sediment with metals of Ni and Cr ºand low risk level of sediments. The Statistical analysis showed that metals Pb,Zn,Cu,Cr may have originated from anthropogenic sources ; As can originate from natural process and Ni seems to have both natural and anthropogenic sources.

The wetlands as the rich and fertile ecosystems may have the crucial role to socio-economic plans and can be more important in environmental plans. This study was done in 2015 to environmental risk assessment of drying up the reservoir number 4 and 5 of Hoor-Al-Azim wetland for develop the Azadegan oil field, using multi criteria decision making methods (TOPSIS). Hoor-Al-Azim wetland is located in the Iran-Iraq border, in Dashte-Azadegan county in south western of Iran in Khuzestan province. In this study first the Delphi method was used to identify risks in the area. 25 risk factors were recognized in 3 groups of physico-chemical risks, biological risks and socio-economic and cultural risks. In order to analyze and prioritize the identified risks the TOPSIS method was used. According to the TOPSIS method, the risks were prioritized to 3 criteria (severity, probability and sensitivity of the receiving environment). Results showed that creating centers of dust with weight of 0.828422 and leakage of oil pipelines with weight of 0.82658 as the most important risks and Reduction of livestock in the region with weight 0.089965 was the least important risk was identified. Finally, management strategies presented for risks control and risks reduction.

In recent years, in order to solve problems were presented the way tasks in the agricultural sector. Among these, growth simulation models have been provided for water management, which it possible to reduce the difficulties in agricultural water. The main advantage of these models is that, they can optimize irrigation schedule economically. SWAP model is of the most widely used models in the world which has shown good results for variety of crops. So that, in this practice the performance of this model for simulating the growth of Canola was evaluated according to the data relating to two cultivation periods in Badjgah. The studied parameters consist of soil water content, evapotranspiration, dry matter, and seed yield. The results indicated that, in the calibration and evaluation phases for seed yield respectively, mean normalized error was 8.0 and 14.2. What is more, mean normalized error for simulation of dry matter was 3.9 and 10.8 in calibration and evaluation periods, respectively.

Iran is located in arid and semi-arid regions in the world and therefore, drought monitoring has an important role in there. Drought assessment is conventionally based on drought indices such as Reconnaissance Drought Index (RDI). On the basis of definition, Reconnaissance Drought Index is estimated by fitting Log-normal distribution on the ratio of precipitation to potential evapotranspiration (calculated by Thornthwaite method). In this research, the effect of the change of distribution function and potential evapotranspiration calculation method was investigated in estimating Reconnaissance Drought Index in Iran. For this purpose, meteorological data of 30 synoptic stations were used in the period of 1960-2014. The potential evapotranspiration was calculated using the FAO Penman-Monteith as standard method. Beside standard method, 20 different methods were used to calculate evapotranspiration value. The superior evapotranspiration calculating method was obtained using Root Mean Square Error statistic. Then, the Reconnaissance Drought Index values were calculated using different evapotranspiration values and by fitting several probability distribution functions. On the basis of obtained results, the change of probability distribution function and evapotranspiration calculation method can affect the determining Reconnaissance Drought Index. Also, the comparison results of the calculated Reconnaissance Drought Index based on the fitting the superior probability distribution function on the ratio of precipitation to potential evapotranspiration which was calculated using superior and standard methods showed that the FAO Penman-Monteith method should be used in 90% of the studied stations to calculate Reconnaissance Drought Index in cases of data available.

Wave breaking in the nearshore zone and then its run up are the main reasons for erosion and destruction of coasts. This causes huge human and financial disasters. Recent coastal protection approaches are based on ecological and environmental balance on the coasts. One of the new coastal protection methods against destruction of waves like tsunami is planting coastal forests that named “coastal green belt”. Coastal forest protection to decrease destruction is based on increasing flow resistance. Therefore, the present study is with purpose of the coastal forest effects on variations of force and inundation of broken waves. For this respect, all of the tests were conducted for 25 heights of incoming waves to Nearshore model with 9% slop in two with and without coastal forest in a flume with length of 8.3m, 0.8 m width, 0.5m height and equipped to a force measurement system. The results of the study show that the coastal forest cause the maximum destructive force and inundation depth of broken waves of an average mitigation of 74 and 40 percent, of 74 and 40 percent, respectively.

Stilling basin with multi-horizontal submerged jets is a new type of energy dissipater structure which causes to collapse excess energy by guiding the supercritical flow through jets and forming submerged hydraulic jump. The important advantage of this type of structures is to eliminate effects of high Flow velocity near to bed and negative bed pressure. In this study the characteristics of hydraulic jump in stilling basin with five parallel submerged jets have been investigated and results are compared with the previous studies also series of experimental equations provided for estimating of the flow characteristics in the multi-horizontal submerged jets. Experiments were carried out in a flume with 15m length and 80cm width. The model of jets has been made from PVC sheets and Froude number varies from 1.5 to 5.We concluded that the energy dissipation rate of submerged jets is approximately 25 percent more than that of the classical hydraulic jump. Length of the jump and length of the roller for multi-horizontal submerged jets were found to be larger than classical hydraulic jump. But for Froude number more than 4, the roller length for multi-horizontal submerged jets is less than the roller length of classical hydraulic jump with the same Froude number; the difference will be larger as the Froude number increases.

In order to study the effect of water and nitrogen stress on biomass in Maize variety KSC704, an experiment was conducted at Agricultural and Natural Resources Research Center of Neyshabour city in year 2013. The experimental design was randomized complete block with three replications. The main treatments consisted of two levels of water stress 80 and 60 percent of water requirement in each of the three stages of growth vegetative, reproductive and grain filling and secondary treatments of two levels of 100 and 50 percent nitrogen. Most of biomass was produced in the control (no stress) equal to 22.8 ton/ha. Water and nitrogen stress applied at different stages of growth, has decreased final biomass. Water and nitrogen stress at vegetative growth stage had highest effect on biomass and lowest biomass was measured in IR60N50 equal to 13.2 ton/ha. Statistical analysis of results also showed that effects of water and nitrogen stress and interaction effects of irrigation and nitrogen had significant effect on biomass and water use efficiency at 1 percent level. The highest water use efficiency were obtained in control (I100N100) treatment with 1.77 kilograms per cubic meter. According to the results, it is recommended to maximize water use efficiency, water and nitrogen use completely done.

In this paper, the effect of tube diameter (Dp) in measurement of shear stress (tb) of the boundary layer wall was investigated under a zero pressure gradient. For this purpose, four different tubes with outside diameters of 3.2, 3.9, 4.7 and 6.3 mm were used which are corresponded to Dp/d of 0.039, 0.047, 0.057 and 0.076, respectively. Measurement of the pressure difference of static point and total in Preston tube was implemented using a differential pressure transducer with accuracy of 0.2 percent of the original scale. The results of the shear stress measurements around Reynolds numbers from 6.4×104 to 39.87×104 using Patel and Bechert calibration equations showed that the Preston tube diameter has a significant impact on the shear stress estimation and both equations are sensitive to the tube diameter. The maximum value of difference in the shear stress measurements tb of different tubes using Patel calibration is about 9%, while the Bechert calibration gives a maximum difference of approximately 14%. Comparing results obtained from both Patel and Bechert calibration equations showed that variation in result of the two equations is minimum when the diameter Preston tube is 3.9 mm.

Water productivity is one of the indexes which is widely used in the issues related to crop productivity and water, and is defined as the ratio of the amount of crop yield to the amount of water consumed by the crop. The water consumed by the crop may be supplied by rain, Irrigation or even irrigation plus precipitation. In fact water productivity is an indicator of the amount of production for each unit of consumed water. In this study, the amount of annual water productivity was indicated according to the available information and six years data-set, and then the mean value was reported for network’s crop water productivity. In this practice, ten networks namely, Avan, Dez, Shavoor, Maroon, Fajr & Jaizan, Gotvand, Karkhe, Ramshir and Shadegan were studied. Water productivity of the networks was estimated according t o the crop yield and the volume of consumed water. The highest rates belonged to Avan, Gotvand and Shadegan, being 1.03, 0.98 and 0.85 Kg.m-3 while Ramshir with an average water productivity of about 0.44 Kg. m-3 had the least value. An analyze over the relationship between crop yield and irrigation shows that, wheat crop yield will increase until the time that the crop’s water requirement is supplied, but it does not change or even decreases when the amount of applied water goes beyond the crop’s water requirement, thus as a result, the water productivity decreases.

Triangular vanes attached to the bank are a new method to control erosion and help protection the bank in meandering rivers. This structure is subjected to scouring due to flow convergence at the tips of the structures. Therefore, countermeasure methods should be employed in order to prevent financial damages and life hazards. One of these methods is to use a slot. In this study, the series of triangular vanes that a parallel chord rectangular slot, with the opening of the full vane area of 10% and a ratio of a/b=4 (a and b are the length and width of the slot) the bed in which they are established position near has been used. The vanes angle is 30 degrees upstream of the bank. Experiments under different installation distances, 4, 6 and 8 times the effective vane length, hydraulic conditions are different (Froude number 0.287, 0.304, 0.322), and the clear water. In all experiments depth of flow is constant and equal to 14 cm. Then the results were compared with no slot. The results showed that the slot reduces the average depths of scour around the tips of vanes. In average, the reduce percent of the average scour depths around the tips of the structure in distances 4Le, 6Le and 8Le is equal to 9 percent, 17 percent and 18 percent respectively. The triangular vanes caused flow diversion from outer bank towards the center bend and thus the formation of thalweg. The slot reduces the maximum depth of scour thalweg. In average, the reduce percent of the maximum depth of scour thalweg in distances 4Le, 6Le and 8Le is equal to 22.6 percent, 46 percent and 30 percent respectively. The first of effective length of vanes was 1/5 flume wide. In start tests and erosion around the vanes increased the first of effective length of vanes. The slot reduces the effective length variation of vanes. In average, the reduce percent of average the effective length variation of vanes in distances 4Le, 6Le and 8Le is equal to 15.5 percent, 13.7 percent and 15.7 percent respectively.