Showing 6 results for Irrigation Network
Mohammad Reza Yazdani, Sayed-Farhad Mousavi,
Volume 1, Issue 2 (10-1997)
Abstract
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.
T. Sohrabi, U.a. Khoshkhahesh,
Volume 3, Issue 4 (1-2000)
Abstract
The purpose of this research is to determine the application efficiency of rice irrigation plots and to analyze the reasons for low efficiency. The study will also try to determine the effective factors which could increase the application efficiency of rice fields. The selection of rice fields was based on climate, soil characteristics, and farmer management. Water application efficiency was determined by field measurements in three modern irrigation networks named Fouman (F), Rasht (G) and Lahidjan (D). In the meantime, a traditional network was included for comparison. In the study areas, the soil texture was heavy with an infiltration rate of less than 3 mm/day. The study was carried out under two different conditions: (1) without return flow and (2) with return flow. In the first case, the average application efficiencies in Fouman (F), Rasht (G) and Lahidjan (D) were about 51.2, 49.0 and 49.4 percent, respectively and the maximum and minimum values were about ((52.6, 49.7)), ((50.7 , 47.3)), and ((50.7 , 48.0)) percent, respectively. In the second case, the average application efficiencies for the above-mentioned regions increased to 73.4, 73.3 and 72.4 percent, respectively and the maximum and minimum values were about ((74.3, 72.4)), ((74.3, 72.1)), and ((73.0, 71.5)) percent, respectively. Runoff ratios in the above-mentioned regions were 30, 33 and 31 percent, respectively. During growing period (from transplanting to harvesting), the average applied irrigation water was about 1130 mm (11300 m3/ha) and the average evapotranspiration was determined to he about 561mm.
M. J. Monem, M. R. Alirezaee, E. Salehi,
Volume 6, Issue 4 (1-2003)
Abstract
Recent studies have shown poor performance of irrigation systems, which indicates the requirement for special attention to performance improvement. The first step for improving the performance of irrigation systems is evaluation of the present situation. Performance evaluation methodologies presented so far are either qualitative such as DA (Diagnostic Analysis), RA (Rapid Appraisal) and FA (Framework Appraisal), or they are similar to classical methods even if they produce quantitative indicators. They fail to introduce performance standards. In this study, using Data Envelopment Analysis (DEA), which is a quantitative method and produces realistic standards, 8 irrigation systems were evaluated and their performances were determined. With respect to the number of decision-making units, inputs, outputs, and corresponding returns to scale for irrigation systems, a suitable DEA model was selected. Capabilities of DEA allow for separate treatment of performance evaluation of overall irrigation network and its operating company. This feature is implemented using different technical and operational indicators.
The results indicated that Zayandeh Rood irrigation system, among the 8 irrigation systems, has the highest technical efficiency. Minab and Varamin systems have the lowest technical efficiencies. Golestan and Behbahan Networks perform well, although their operating companies are inefficient. Garmsar, Ghazvin, and Moghan systems, although not inefficient, have some improvement potentials. In general, with respect to the capabilities of DEA in performance evaluation of irrigation systems and indicating appropriate standard, it can be concluded that this technique is quite efficient and successful for performance evaluation and improvement of irrigation systems.
M. A. Moradi, A. Rahimikhoob,
Volume 16, Issue 62 (3-2013)
Abstract
Reference evapotranspiration (ET0) is a necessary parameter for calculating crop water requirements and irrigation scheduling. In this study, a method was presented as ET0 is estimated with NOAA satellite imagery in the irrigation network. In this method, a pixel from a set of pixels within the irrigation network was chosen with the highest vegetation index, and its surface temperature (Ts) with extraterrestrial radiation parameter (Ra) was used as inputs of the model. The M5 model tree for converting Ta and Ra to ET0 was used as input variables. In this research, Gazvin irrigated area was selected as a case study. A total of 231 images of NOAA satellite related to irrigation season of the study area were used. The results obtained by the M5 model were compared with the Penman–Monteith results, and error values were found within acceptable limits. The coefficient of determination (R2), percentage root mean square error (PRMSE) and the percentage mean bias error (PMBE) were found to be 0.81, 8.5% and 2.5%, respectively, for the testing data set.
R. Jamali, S. Besharat, M. Yasi, A. Amirpour Deylami,
Volume 22, Issue 3 (11-2018)
Abstract
The irrigation and drainage network of Zarrinehroud with an area of 65,000 hectares is the most important network of Lake Urmia basin, with the direct link to the lake. With the current crisis in the lake, an assessment of the existing network's performance is essential in the Urmia Lake Rescue Program. The purpose of this study was, therefore, to evaluate the transmission, distribution, and utilization efficiency and irrigation efficiency at the surface of the network. Three products were selected from the cultivar with the highest crop area (10% beet, 22% and 22%, and 38% wheat). The dominant method of irrigation was surface irrigation. At the network level, soil moisture in the field before and after irrigation, soil physical and hydraulic properties and water use volume for irrigation were measured. The results showed that the average transmission efficiency in canals with the concrete coating of the network was about 79%, which was in the range of 33% (in the smaller channels) to 100% (in the larger channels). The water distribution efficiency in the network was, on average, 76%, varying from 50% to 100%. Water use efficiency in the fields based on soil moisture balance analysis varied from 41% in the sandy loam soils to 66% for the clay texture. Based on the analysis of the data on the amount of harvest, production costs and product sales price, the water use efficiency (in kilograms of product per cubic meter of water used) varied from 0.4 for the elderly hay to 5.1 for the sugar beet. The amount of water used in this network (in Rials per cubic meter of water consumption) was between 2740 for alfalfa aged over 10 years and 6900 for wheat. It can be concluded that in the case of water constraints, wheat, sugar beet and alfalfa could be the most economic cultivar, respectively.
H. Nozari, S. Azadi, V. Rezaverdinejad,
Volume 23, Issue 1 (6-2019)
Abstract
Due to the growing population, crop production is one of the essential needs of the society. Since soil and water salinity can have a great impact on the crop yield loss; so, the appropriate irrigation method can be applied to reduce these effects. In this study, the system dynamics model was developed using VENSIM. The model simulated the effect of salinity and water stress on the crop yield, moisture and salinity of the root zone. In order to calibrate and validate the model results, 9 treatments data were collected from the Right Abshar Irrigation Network, on the Zayandehrud basin. After statistical analysis and calculation of RMSE index and the standard error, the fit between the measured and simulated crop yield, the moisture and salinity of root zone was calculated. The average of these indexes for all treatments was 2776.98 kg/ha and 0.07 for crop yield, 0.026 and 0.09 for soil moisture and final, 0.54 dS/m and 0.08 for the salinity of root zone, respectively. The results showed that the model could be calibrated accurately and completely in estimating the crop yield with the reasonable accuracy.
