Journal of Irrigation Sciences and Engineering
Year:2014 | Volume:36 | Issue:4|Papers Count:12

Sedimentation in manmade reservoirs is inevitable and density current is one of its effective factors. Since the force due to flow in the plunge region changes from momentum to flux, so identification of characteristics of this region is very important. In this research, geometric parameters of underflow density currents in plunge region under different inflow concentration, bed slop and inflow discharge. Experiments were conducted in a flume in Hydraulic Laboratory of Water Sciences Engineering Faculty of Shahid Chamran University of Ahwaz. In the experiments, plunge depth, plunge region length and the height of the flow at the end of this region in different discharges, four different concentrations equal to 1006, 1009, 1013 and 1016 kg/m3 and three slopes equal to 8, 12 and 16% were measured. The results show that, plunge region length and the height of the flow at the end of plunge region are functions of plunge depth.

Hor-Al-Azim wetland is located in southwestern of Khuzestan province in Iran in the Iran-Iraq border. In و 1377 Iran started to use the biggest dam on the Karkeh river. This river is one of the largest water sources of Hor-Al-Azim wetland. The dam is designed to irrigate 32000 hectares of lands in Khuzestan plain. This study was conducted to evaluate changes in the quality and quantity of entering water into the wetland due to Karkhe dam construction and also precipitation change using long time data. The required data was collected from three hydrometric stations in the Karkheh watershed including Hufl, Nissan, and Hamidieh. Data analysis showed significant differences between quantitative and qualitative parameters of Karkheh river in Hamidieh hydrometric stations in the periods before and after the Karkheh dam construction. The results showed that the lower quantity and quality of the entering water to the wetland for these years was due to combine effects of lower participation rate and also reducing flow rate as a consequence of dam construction.

In this study, the effect of magnetic water on the soil saturated hydraulic conductivity has been investigated by a quite random form with four treatments and three repetitions. Treatments in this study were included: 1- potable water after passing through the RPM device with 500 Gauss Intensity; 2- potable water after passing through the Aqua Correct device with 1300 Gauss Intensity; 3- potable water after passing through the Elcla device with 1600 Gauss Intensity; 4-potable water without magnetic device(Reference treatment). Hydraulic conductivity was measured by constant head test.12 high pressure plasticpipes were used for preparation of the soil columns. The columns were fixed at new metal table with constant height form the ground in order to gather the drainage, easily. Also agricultural soil with loamtexture was compressed into the columns up to 15 cm. During 35 days, the water with 2 cm height was passed over the top of soil columns. At the end of 35 days, magnetic water had significant effect (1%) on decreasing saturated hydraulic conductivity. The third magnetic treatments had lowest hydraulic conductivity that it was 51% less than reference treatment. For the first and second treatments, it was 29.3 and 36% less than reference treatment, respectively.

Determination of the fall velocity of cohesive sediment particles is very complex because of the adhesion properties of cohesive sediments and flocculation phenomenon. Therefore the deposition of fine sediments was investigated using an annular flume and in this work the hydraulic parameters was measured using Acoustic Doppler Velocimeter (ADV). Based on the experimental results the fall velocity of cohesive sediment was determined for different shear stresses values and different concentrations based on some empirical equations. The obtained results showed that a good agreement was observed between the Krone's equation and Burban's relationship. The obtained result from Lou and Krishnappan's method was inversely comparison the aforementioned equation. Finally, the results showed that the fall velocity is depended on the flow shear stress as well as the sediment concentration.

Water-hammer is a transient condition which may occur in a network as a result of rapid or slow valve closures, pump failures, etc. It creates high and low pressure waves which travel along the system and decay as a result of wall shear stress. Comparison of experimental and theoretical results revealed the failure of steady or quasi-steady models in correctly predicting the damping process of the pressure waves. The aims of this research are to increase the number of available unsteady velocity profiles and to give a contribution to the understanding of transient flow dynamics and energy dissipation. With this purpose, experimental measurements by Ultrasonic pulsed Doppler Velocimetry of the unsteady velocity field for water hammer transients in a long polyethylene pipe, caused by a downstream sudden valve closure, and are presented. Velocity data are analyzed and compare with results obtained by other authors. Result show the inherent weakness of UDV velocimeter, to measurement of flow rate near the conduit wall, for two reasons: low velocities and reduced dimension of effective sampling volume. By use of corrective method represents the non-symmetric velocity profiles and vortex formation in the conduit wall.

A textile factory discharges its effluent into GamasiabRiver without any treatment. In order to evaluate environmental side effects of this factory a routine phyto test was conducted with the common duckweed (Lemnagibba). The duckweed in the Hogland solution was exposed to series of concentration of the factory effluent. In this study Lemnagibba was exposure to five different concentration of textile effluent for 7 days.Plant growth response was measured by two methods: counting the number of fronds and measuring the chlorophyll content (chlorophyll a, b and total chlorophyll) of the duckweed. MC50 values was calculating in 3, 5 and 7 days.3 days: 77.77ml/l, 5 days 59.7ml/l, 7 days 69.34ml/l. Single factor analysis of variance (ANOVA) showed that in all of concentrations, difference in the values of total chlorophyll content and chlorophyll a were significantly (0.05≥0) different with those of control. Similarly, difference number of fronds was significant (0.05≥0) only in 7 day.

The need for water storage is steadily growing because of increasing water demands due to growing population in arid and semiarid areas such as Iran where droughts occur in succession. The use of superabsorbent polymer materials in agriculture is one of the considered approaches to improve the soil structure in semi- heavy and heavy soils. In this study, the use of superabsorbent A300 and its effects on saturated hydraulic conductivity, available water content, porosity and moisture characteristic curve was evaluated in silty loam soil. A completely randomized design with four levels (zero, 1, 2, 3 g/kg soil) and three treatments was used for statistical analysis in research field of Shahid Chamran University. The results show that increase 1.68 saturated hydraulic conductivity soil in 0.3 weight percent to the control.The increase of porosity for treatments0.1, 0.2 and 0.3 weight percent of controls versus 8.03, 9.76 and 22.11 respectively. Statistical indicators applied in RETC software shows the Van Genuchten model (m=1-1/n) has the best simulation accuracy by comparing the observed and predicted soil moisture values.

Inhabitants of the arid climate have led to greater use of groundwater. On this basis because of the importance of water resources, the quantity of groundwater in the plain of Neyshabour during 2002 to 2008 was evaluated. Visual MODFLOW software was helpful in this regard. The results showed that hydrodynamic coefficients are relatively high in plain of Neyshabour. This property can be very effective in the fields of artificial recharge projects. Also due to the high correlation between observed and calculated data from the model calibration, results are acceptable in all observation wells. Studies showed that groundwater in the plain of Neyshabour has dropped highly due to the excessive travel, drop in water levels in different regions according to different feeding and discharging aquifer. The map of stone floor level shows that the context of the postal and the mountain aquifer Neyshabour is high and concave mode. Feeding rate calculated in the Binalood lower elevation are more than other areas due to seasonal flooding into this area are flowing of the highlands. The results showed a continuing trend of regional drainage wells in some areas, so groundwater quality and quantity is reduced.

Root system is effective on increase soil shear strength. This study investigates the root system of Tamarix trees on slope of riverbanks. Five trees (from TAMARIX species) which grow on the river beech were selected in a distance about one km on SAIMEREH River in Ilam Province. Circle profile trenching method was employed to obtain characteristics. Results show that the number of roots on upslope is about 22 percent more than downslope. For all diameters, the number of roots in upslope is more than downslope. The average of root diameters on downslope is bigger than upslope. Total root area on upslopeis about 27.6 percent more than downslope. It is concluded that root system on riverbank is unsym metrical and slope has effect on the root system. The number of roots and root area on upslope was more than downslope.

Canopy temperature is an important factor for irrigation scheduling. This is because canopy temperature is depend plant water status. This research evaluated usefulness of Modis sensor for estimating wheat canopy temperature. Relationship between temperature and values of digital satellite images were determined on different levels of plant height and then models were evaluated. Based on the results, the best correlation between the temperature of the green cover were with band 34& 25, band 3 and band 2 in the special resolution of 1000 m, 500m and 250m respectively, and RMSE was equal to 3.6, 3.6 and 5.3 in the special resolution of 1000 m, 500m and 250m respectively. Lowest error was observed at the top of canopy and maximum error was at the bottom of plant. Result showed that measuring canopy temperature by using remote sensing is possible but magnitude of error showed that models need some modification