فصلنامه علوم و مهندسی آبیاری
سال سی و هشتم شماره 2 (تابستان 1394)

Low flow is one of the very effectual hydrologic parameters on the state of aquatic ecosystems as well as power production, reservoir management and industry. Therefore, it is necessary to investigate the changes in this parameter in the future periods under affecting factors such as climate change. In this regard, the impacts of climate change on low flows of Sepid dasht sezar catchment were evaluated, in this research. First, the ability of IHACRES rainfall-runoff model for simulation of low flows of this catchment was evaluated. After calibration and verification of model, in this study observed that the model has a good ability for simulating of mean daily flow (R2-log>0.7), also low flow (R2-inv>0.6). In addition, the ability of model to low flow indices (including Q95, AM7Q with different return period and QdefS)was evaluated. Then, The outputs of the temperature and precipitation of 10 general circulation models of the atmosphere under A2 emission scenario was used in order to assess the effects of climate change over the period 2015-2044. LARS-WG model was applied for downscaling of the output of these 10 models. Finally, downscaled values ​​of temperature and precipitation were introduced to the IHACRES rainfall - runoff model and the low flow in the future was assessed based on the low flow indices. Changes of two indices Q95 and AM7Q in the future period to the past, based on the median of 10 AOGCM model results is decreasing (-40% for Q95 and from -52% to -79% for AM7Q with different return period). Also, the QdefS index show the increasing change (30% based on the median of AOGCM model results). All three indices have confirmed each other's results and show that the expected climate change in the future, greatly affect the low flows.

Using of spur dikes is one of the usual methods in river engineering for river bank protection against erosion and destruction due to water flow. In this research the influence of Bandal-Like spur on the erosion pattern in non-submerged conditions was investigated. Experiments were performed in clear water condition, considering 3 spaces between Bandal-Like spurs, 3 placement angels of Bandal-Like spurs and 4 discharges in 45%permeability of Bandal-Like spurs. The results indicated that maximum depth of scouring was occurred around first Bandal-Like spur. Also in a constant Fr, the maximum depth of scouring decreased with increasing space between Bandal-Like spurs. Finally the impact of placement angel of Bandal-Like spurs on the maximum depth of scouring with degrees of 60, 90 and 120 degree was investigated. The results showed that the maximum depth of scouring in degrees of 90 and 60 degree are maximum and minimum, respectively.

One of the important challenges for water resource researchers is Integrated Water Resource Management (IWRM). Indeed, IWRM is conjunct surface- ground water operation for sustainable water use and increase of available water. Hence, normative planning in this area requires knowledge of surface- ground water interaction process, estimation of effective parameters and factors affecting inside the system. So the basic objective in current study is surface- ground water interaction simulation in terms of dynamic coupling between ground and surface water in Dez plain (consist of five under plain: Loor, Dimcheh, Dez-Gharbi, Dez-Sharghi, Sabili). When properly linked, data and results flow back and forth between WEAP and MODFLOW for each calculation time step and for any feedback WEAP value for groundwater infiltration and abstraction, river stage and surface runoff will be sent to MODFLOW as inputs for its calculations, and MODFLOW results for (head), lateral flow between aquifers, and etc. come back to WEAP as inputs for its calculations. Results illustrate that in northern to central parts of the plain, aquifer recharge by Dez and Karkheh rivers. Most of the times these rivers in central to southern parts of the plain act as drainage (such as other rivers in Dez plain). Simulation results illustrate that due to operation of deep wells as the only available water source in Loor, Maximum drawdown was done in this area. However water table increased in Dimcheh. Generally in areas of Dez plain, where focuses on sustainable conjunctive use of surface and ground waters, water demands will be coverage more than 80% by surface water and 20% by ground water.

In this study, a three-dimensional hydrodynamic model (ELCOM) coupled to a water quality and ecosystem model (CAEDYM) were used to simulate limnological processes, stratification and mixing, and prediction of the released water quality in the proposed designed reservoir in southwest Iran (Abolabbas Reservoir). Also, investigating and defining the appropriate outlet levels on the dam wall was the other prospective of this study. Different scenarios were analyzed and designed to simulate different conditions of drought periods in different severities. The results indicated that, in all scenarios, the reservoir regulated the inflow quality parameters very well via both power plant and irrigation outlets. No hypolimnetic anoxia were observed in the reservoir in normal conditions. The simulation of drought scenarios showed an overall degradation of all parameters when the drought severity increases. The drought affected the dissolved oxygen concentration directly as one of the major environmental water quality indices. During the worst drought scenarios, the anoxia in a 40-meter bottom layer of the hypolimnion throughout the year and the anoxic outflow for 5 months were observed. In order to reduce the hypolimnetic anoxia, a scenario with a decreased bottom outlet by 10 meters below the designed level (to be 14 meters below the irrigation outlet) and hypolimnetic withdrawal was designed and simulated. While the irrigation outlet was closed, the hypolimnetic withdrawal via bottom outlet reduced the anoxic layer from 40 to 20 meters thickness and also reduced the anoxic outflow from 5 to 3 months.

Intensifying contamination of Shahrekord aquifer has been already understood and documented by periodic sampling, use of simple statistical indicators and established procedures. However, integrated management of aquifers requires improved methods. The main purpose of this study was to detect changes in both nitrate and phosphorus pollution of Shahrekord groundwater over a period of four years (2006-2010) by an integrated index. For this purpose, nitrate and phosphorus maps were normalized by WHO standards, converted to rank maps and then, integrated maps of nitrate and phosphorus were produced for both years of 2006 and 2010. Changes of integrated index over this 4-year period were obtained by differencing the two maps. Integrated map was strongly correlated with nitrate map (r=0.94) and with phosphorus map (r=0.87) indicating it properly reflected the distribution of both contaminants. Difference map showed a minimum of 2%, a maximum of 4% and on average 2.8% of increase in contamination. During this period, in approximately 5.3% of the aquifer, water quality deteriorated. Compared with phosphorus, nitratehas a greater share inShahrekord aquifer contamination but over this period the phosphorus’s share has increased. Applying the procedure used in the present study, enables the managers and planners to quantify trends in aquifer contamination more accurately. Also, with this method, the relative involvement of each contaminant in pollution, at the beginning and end of a time interval, can be estimated. An integrated map and its affiliated integrated index of nitrate and phosphate in groundwater appears to be useful for the assessment of algal growth and its consequences such as clogging of low-pressure irrigation pipes, water smell and taste deterioration and increased cost of treatment.

Local scour around the bridge piers results from the flow impact with bridge piers and it’s streamline separation. The scour hole around the bridge piers depend on the hydraulic characteristics of the flow, the specifications of the fluid, the pier’s shape and the size of the bed material. In most experimental study on scour around the bridge piers only one size of bed material is used. In this study the local scour around the cylindrical bridge piers with diameters of 10, 20 and 40 mm are measured and analyzed in a laboratory flume. The flow condition was clear water with relative velocities of 0.95, 0.86 and 0.76. Two uniform bed materials with mean diameters equal to 0.5 and 0.7 mm are used. The results indicated that in the constant hydraulic conditions for all piers diameters, the equilibrium time for maximum depth scour increases as the grain diameter of bed material increases. Also as the bed material increases from 0.5 mm to 0.7 mm, the depth of scour hole decreases when the diameter of pier was 40 mm and the relative velocity was 0.95 and also when the pier diameter was 10 mm and the relative velocity was 0.76. The amount of scour depths decreases for above mentioned piers were equal to 1.2 times and 4 times respectively.

Since the one of the application of piano keys weir is use in irrigation and drainage network, and it is possible that with decrease of discharge, the water level during dehydration is faced with a drastic reduction. Therefore, by creating Parapet wall with the ability to change slope, can be allowed to weir, that any decrease in discharge, keep the water level at a certain level. In the present study, the important parameters affecting the discharge rate including of P/Wu, (weir height, P, to within one cycle width, Wu=Wi媏뙎) and sloped parapet wall were investigated. Then the equations of discharge coefficient with modifying the general equation weirs and dimensional analysis were obtained. To achieve these purposes, the parapet walls were built at three angles 3, 5.5 and 8 degrees in the direction of flow (positive) and the opposite (negative), on two piano key weirs, with ratios of P/Wu=1.33 (Model 1) and P/Wu=0.5 (model 2).The experiments have been carried out on a experimental flume with a width of 80cm, length 10m and a height of 60cm. The results showed that the model 1 with negative slope of 3 degrees can discharge more than the ogee weir (approximately 2.4 times). In addition, the derived relationship for the discharge coefficient (sloped parapet wall) had R2 equal to 0.978 and statistical indicators NRMSE and WQD equal to 0.0214 and 0.018, respectively.

Effect of the shore green belt on reduction of wave height and energy of the attacking waves is studied. Experiments are conducted for two patterns, triangular spaced 5 × 5 and 10 × 10 cm, 3 width of 10, 30 and 40 cm, 5 shore slopes of 0, 3, 5, 7 and 10% and 5 wave heights of 1/5, 3, 4, 6 and 8 cm. In total, 325 different cases were examined. Dynamic pressure was measured at several points of the shore model by pressures transducer. The wave force absorbed by the green belt was measured directly by a system of load cell. Results showed a considerable effect of green belt on reduction of wave height and energy. For all of shore slopes, the maximum of momentum absorption and wave height reduction was in 5×5 pattern and width of 40. The force absorption for spaced 5 × 5 was more than 10 × 10. The average rate of force absorption, between 5 × 5 and 10 × 10, was 1/3.

Interpolation method is one of the most important techniques which have been used in zoning studies. In order to obtain the continuous and integrated maps and predict unknown values, the interpolation method has been used. Since measuring ground water levels is very difficult and costly, therefore the iso-water table maps are used. The main purpose of this research is to compare two geostatistical methods concluded Kriging and IDW methods in order to interpolation groundwater level of the West, South and South-West of the Urmia Lake. In the present study water level data of 634 piezometric wells located in the West, South and South-West of the Urmia Lake in the West Azerbaijan have been used in the period of 2010-2011. Stationary and independence of data were tested using Wald and Wolfowitz methods. Iso-water table maps were drawn using Kriging and Inverse Distance Weighted (IDW) methods. The result showed that the Kriging method has better results than Inverse Distance Weighted method.

Interaction between water flow and bed erodibility, which is associated with sediment transport and creat bed forms. Ripples are the smallest of the bed forms. Experiments were performed with variety slopes of 0.0005 to 0.003 and discharges of 10 to 40 L/S, on the artificial ripple in the hydraulic Laboratory of Shahrekord University.Velocity measurements were collected using an Acoustic Doppler Velocimeter. It was observed the peak value of bed shear stress was appear on the midpoint of upstream surface and the lowest value appear on the crest. From the crest to trough, the general bed shear stress was in a trend of increasing. It was also observed that in the case of ripples bed forms were consist of about 26% of total bed shear stress.

In this study, raw and treated wastewater of Serkan Wastewater Treatment Plant, located at 70 km east of Hamedan, were reused for potato irrigation under lysimetric conditions. The factorial experiment executed with a statistical completely randomized design in three replicates and two factors. The factor of watering programs which were categorized as follows: Raw wastewater (T1), treated wastewater (T2), a combination of 50% raw wastewater and 50% fresh water (T3), a combination of 50% treated wastewater and 50% fresh water (T4), and fresh water (T5). The factor of soil cores depths which were depths of 0-10 cm and 10-20 cm. The effects of watering treatments were significant on accumulation of Mn, Fe, Cu and Zn in the soil layers. Also the interaction effects were non-significant on accumulation of Mn, Cu and Zn. The interaction effect was significant on the Fe concentration. The maximum and minimum Mn, Fe, Cu and Zn concentration in the soil was obtained in T1 and T5, respectively. Also, the Mn, Fe and Zn concentration decrease with soil depth but concentration of Cu increase. Overall, based on the accumulation of heavy metal in the soil, the watering treatments were ranked as follows: T1> T3> T2> T4> T5. Based on the accumulation of heavy metal in the soil, heavy metals were ranked as follows: Fe> Mn> Zn> Cu.

River channel confluences form one of the most important morphological elements in river systems. The entry of a lateral inflow into the main channel generates substantial changes to the flow velocities and turbulence, and result in characteristic patterns of scouring and deposition. Junction angle has highlight effect on flow pattern in open channel junction. In this research the capability of SSIIM1 model to simulate the 3D flow at channel junction and the effect of junction angle on its pattern have been investigated. Using the experimental data of a 90° junction flow collected by Weber et al. (2001) in Iowa University the model was calibrated and validated. Good agreement is obtained between simulated velocity profile and water surface mapping by the SSIIM1 model and the experimental measurements so that the maximum error to predicted water surface and velocity value was about 3% and 10% respectively. The model is then applied to investigate the effect of three junction angles (45, 90 and 135°) on the flow characteristics such as: Bed shear stress, separation zone dimension, and secondary flow pattern and water surface and velocity profiles. The result showed increasing junction angle leads to higher separation zone dimension. For 45o junction angle a clear separation zone has not appeared. Shape index of separation zone (wide to length ratio) were calculated as 5.8 and 7.45 for 90o and 135o junction angle, respectively. The ratio of upstream depth to downstream depth of junction is 1.05, 1.06 and 1.09 for 45°, 90°, and 135°, respectively. Also the result indicated that increasing the junction angle from 45°to 135° bed shear stress increases about 80.2%.

The goal of this research was evaluation of tape irrigation levels, 100%, 70% and 40% water requirement (T100, T70 and T40) and furrow irrigation (F) on the yield and water use efficiency (WUE) of summer tomato. The experiment was conducted in a randomized completely block design with four treatment and three replication for two years in Safiabad Agricultural Research Center. The resuls showed that the highest yield was in T100 and T70 with 54.6 and 53.4 t.ha-1 in yield, respectively and increasing yield was 25% higher than Furrow irrigation. T40 treatment with the lowest yield (42.9 t.ha-1) had a significant difference at 1% with T70 and T100. Water use efficiency(WUE) was highest in T40 (11.4 t.ha-1) but there was no significant difference between it and T70 treatment. In a general manner average of WUE in all tape irrigation levels were about 2.3 times furrow irrigation. So T70 treatment was proposed for Khouzestan climate conditions. No significant difference was between irrigation levels on tomato quality characteristics including Acidity, Scorbic acid and Sitric acid but severe deficit irrigation level (T40 treatment) was caused to increase Brix. Although soil salinity was not significant difference between irrigation levels, but it was significant for soil depth, So that average of soil salinity in 0-30 cm was 1.4 dsm-1 which it was 38% higher than 30-60 cm soil layer.

The importance of proper management of water resources in Kerman, because of limited and water resources crisis is very high. This research has been based on two farm included two center pivot systems in Kerman’s Bardsir and Rayen. For this purpose, the evaluated parameters included Application Efficiency (AE), Potential Application Efficiency of Low Quarter (PELQ), Actual Application Efficiency of Low Quarter (AELQ), and Distribution Uniformity of low quarter and half quarter (DU), Christiansen’s Uniformity coefficient (CU) and adequacy of irrigation is calculated. The result of comparing two Center pivot systems is that Rayen’s Center pivot system with a CU, Adequacy of irrigation and also DU are higher, but AELQ is lower than the recommended value and the difference between AELQ and PELQ shows weakness in design, performing of the system and supervision. Otherwise because of proximity between AELQ and PELQ at Bardsir’s center pivot system indicated purposely paucity in terms of management.