عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Water is becoming a scarce and precious resource all over the world. Nowadays, irrigation has allocated 69 percent of the 3240 cubic kilometers of human consumed water and 87 percent of the total consumed water. Transformation of dry lands into irrigated areas with correct operation, reasonable utilization and good maintenance could be greatly effective on increasing of human needed products. Accomplished fact, all over the world is that most of operating irrigation and drainage projects don’t redound to objective points and not only they couldn’t successfully increase efficiency, but they also cause a reduction in production levels by harmful effect on aforesaid resources. Reasons have almost been incorrect design and operation, unsuitable and insufficient utilization and maintenance and generally poor management in different sketches. Ghoorichay reservoir dam is located in Ardabil province. This earth dam has clay core and storage capacity of this structure and usage volumes are 18.07 and 17.71 cubic million meters, respectively. Ghoorichay irrigation and drainage network is situated downstream of the dam, which covers 2200 ha area. Water is drawn from the reservoir and distributed through the main canal and many secondary channels to farms. Main canal is established along the kilometers, 13+347 to 20+317, to convey and distribute water into 4 secondary channels named LC1, LC2, LC3 and LC4. This canal has 6.97-kilometer length, after LC1 turnout from kilometer 13+347 to 15+093 it is generated with trapezoidal cross section, 0.001 slope and 2.25 cubic meters per second discharge. This section of main canal has 1.2 meter wide, 1 meter height and bank slope 1:1.5 (V:H). In this section of the main canal, normal depth is considered 0.75 meters, free height 0.25 meters and normal flow velocity is 1.3 meters per hour.
In this study, the first step to calibrate the gates is to choose the suitable place for flow measuring. So LC2 channel with 6- kilometer length and 20 turnouts considered the most important secondary channel in Ghoorichay irrigation and drainage network, is chosen and one of its slide gates with 1.15 meter width is assessed. It is necessary to notice that the chosen point for measurement should be in a location with minimum swing and wave ruffling to decrease measurement errors in hydraulic characteristics such as water surface width and water depth. In addition, it shouldn’t be any other turnout close by measuring location in order to ignore water losses through the distance. Then, the needed condition for operation should be created. So, water depth behind regulation structures should rise up to FSL or Full Supply Level and keep constant by proper regulation while measuring duration. Under this situation, flow measurement in LC2 channel had done. The present structure at the entry point of channel for measuring discharge is 3-feet Parshal flume. Having measured depth and discharge parameters in specialized points of the channel and considering channel dimensions, turnout and regulator structures, flow condition simulates by hydrodynamic models Root canal and ICSS and results have gotten with 10 different turnout opening.
Considering the amount of off-taking in upstream of LC2 channel and downstream demand of this turnout, which is 600 liters per second, also with considering network efficiency equal to 80 percent and evaporation and head losses equal to 50 liters per second. After inputting data in models, simulation is done for one hour duration and discharge and depth amount is determined. In order to assess introduced hydrodynamic models, and after calibration of two models, this part is allocated to comparison of output results with measured results along studied reach. This comparison is included water depth in turnout and regulator location and simulated water depth along the studied reach. The comparison is accomplished by drawing figures and statistics survey of errors in different points. Finally, comparing the best coincidence of results obtained from each model, with observed condition, the proper model is chosen. Results show that in both simulation dates, 1391/3/20 with entry discharge equal to 0.95 cubic meters per second and 1391/3/21 with entry discharge equal to 0.79 cubic meters per second, calculated error in the hydrodynamic model Rootcanal is fewer and better coincidence with observed data is seen. Although the results show that for ICSS hydrodynamic model the parameters are equal to 5.14 and 4.71 centimeters, respectively, and for Rootcanal hydrodynamic model they are equal to 2.12 and 1.61 centimeters, respectively. These results show better performance of the Rootcanal model than ICSS model for simulation and estimation of flow parameters in irrigation canals.