فصلنامه علوم و مهندسی آبیاری
سال چهل و ششم شماره 2 (تابستان 1402)

Achieving basin runoff estimation requires a more realistic simulation of the precipitation process. Simulation closer to the reality of the process has always been the goal of the researchers. How the first starting point of runoff at the basin level is, leads to different patterns, therefore, is effective in the accuracy of the process simulation. The lagged pattern of flow formation in the catchment area, due to the assumption of the formation of the flow from the center of the surface, is closer to the current flow reality than the conventional pattern in simulation, such as HEC-HMS. The present study was designed to evaluate the latent pattern in the catchment area of the Roudzard River, comparing it with the conventional model in the HEC-HMS simulator. The results showed that the lagged pattern, in contrast to the conventional model, increased the number of parameters for the three rainfall events, the values of the Nash and PWRMS were 0.13, -37.0, -0.08 and 2.49, 8.35, 6.41 respectively Which had a lower accuracy in comparison with the values of them such as 0.57, 0.68, 0.43 and 1.03, 6.96, 3.87 in the conventional pattern. However, sensitivity analysis of the parameters indicated the type of pattern is different in the relative sensitivity of the parameters. As in the delay pattern, the K parameter is more sensitive than the conventional pattern compared to the CN parameter. Comparison of two selected patterns in estimating flood volume showed that the delay pattern has a better performance than conventional pattern.

Water scarcity is a big problem in many areas, especially in arid and semi-arid regions. It is rising due to the demand growth driven by increased economic activity and population growth in developing countries. Since Iran is on the world's dry belt and it has rain equivalent to 1/3 of the rain world's average, it is considered a dry country. The rain trend indicates that Iran is going to drought, so plans and measures of water resources management should be developed accordingly (Samadi Broujeni and Ebrahimi, 2010). Also rainfall in Iran is one of the main variables for assessing of water resources, but its spatial and temporal distribution is very Non-uniform. For this reason, the water resources distribution of the country is not uniform, too. Preservation and water resources management are not only a function of rainfall but also depend on the variability of rainfall. If spatial change of rainfall be small, the water resources are more homogeneity and consistency (Mirmousavi and zohrehvandi, 2011) . Hence, the rainfall variations are important in assessing water resources of rivers and the relative study of local and regional water resources. Although various approaches have been proposed for modeling of rainfall, the use of single generators can not properly reproduce the spatial correlations between different meteorological variables. In this paper, was used the first-order Markov chain(MC1), the second-order Markov chain(MC2) and the third-order Markov chain(MC3) for the occurrence of daily precipitation. The Wilks method was used to simulate the occurrence of daily precipitation by preserving the spatial correlation between stations for four synoptic stations in Khozestan province of Iran, considering the importance of preserving the spatial correlation between adjacent stations in water and agricultural studies in daily scale, which has not been studied in Iran up to now.

The analysis of transient flow plays a critical role in designing pipe systems and pipe networks. Controlling and collecting the pressure wave signals at proper spots in the pipeline can provide much information about the system. Many researchers have studied transient flow and the loss caused by unsteady flow (Brunone et al, 1991; Pezzinga, 1999; Vitkovsky et al., 2000).
Compared with steel pipes, the use of polymer pipes such as polyethylene (PE) and PVC in pipelines and pipe networks has attracted much attention due to their superior properties. Researches have been conducted on the dynamic behaviour of these pipes on transient flow. Brunone et al. (1995) explained that pressure wave damping in a polyethylene pipeline is caused by unsteady friction loss; however, the research showed that there is a large difference between the numerical and the experimental results, and this is due to the viscoelastic effects of polymer pipe walls, which were neglected in this study. Soares et al. (2008) examined the viscoelastic behaviour of PVC pipes on transient flow. The creep function of these pipes was calculated by inverse solution of the transient flow. The results showed that the damping, scattering, and shape of the transient pressure waves are fully described by taking into account the viscoelastic behaviour in the developed numerical model. Carriço et al. (2016) studied the uncertainties of the transient flow numerical model in polyethylene pipes, indicating that unsteady friction loss and viscoelasticity of polyethylene pipe walls have parallel effects on transient signals and the effects cannot be simultaneously distinguished.
Most studies have been so far conducted on the transient flow in a simple pipeline made up of steel and concrete. Since few research has been done on transient flow in more complex systems and plastic pipes, the present paper investigates the numerical and experimental model of transient flow and its properties in polyethylene pipe networks in time domain. In this study, by collecting transient signals of the pipe network, unknown parameters are calibrated and extracted by inverse analysis of the transient flow for different discharges. The pressure signal properties in polymer pipes are also compared with discharge variations.

During the last few decades, greenhouse gases have affected the earth's radiation balance by keeping long-wavelength radiation in the atmosphere and increasing the air temperature (Bakht Firouz and Raeini Sarajaz, 2013). The agricultural sector has played an important role in emitting greenhouse gases through using fossil fuels, carbon losses through tillage operations, incineration of crop and forest trees, livestock, the use of livestock manure and construction, and the use of chemical fertilizers. So, the share of this sector in climate change is about 13.5%, of which 60% is related to nitrogen oxide, 39% to methane, and 1% to nitrogen dioxide (IPCC, 2007).
Considering the vast area under cultivation of sugarcane in Khuzestan province and the use of chemical fertilizers as well as the burning of its residues every year, it is necessary to determine the amount of greenhouse gas production in these areas. Therefore, the purpose of this study was to use the DAYCENT model to determine the amount of gas flux emitted in sugarcane cultivation in Khuzestan province and to determine the efficiency of this model with statistics of coefficient of determination, maximum error, root mean square error, model efficiency, and residual mass coefficient. The other purpose of this study is to compare the amount of global warming potential and production of methane, nitrous oxide, and nitric oxide emissions between Shustar and Abadan agro-industrial stations.

This study evaluated a drip-gravity irrigation system implemented in Barajin Park at the north of Qazvin province. In order to carefully examine the existing conditions of the field visit, the effective parameters in the evaluation were measured for all laterals in the selected section, including 13 laterals. The results showed that the water uniformity distribution was unacceptable due to the significant elevation difference. Note that no filtration system was used; hence, it was impossible to use a pressure regulating emitter (PC) because these emitters are sensitive to chemical and physical clogging. To improve the water distribution conditions, applications of 1) using flow control valves, 2) changing the diameter of the pipes, and 3) using two types of conventional drippers (Non-PC) with different scenarios and modeling in EPANET software were investigated.           

The over-drilling of deep wells and the excessive exploitation of groundwater sources cause the groundwater level to decrease daily, resulting in more energy to power pumps. Artificial recharging is the injection of water into a permeable formation to recharge the groundwater aquifer and reuse it with a different regime and quality and by creating additional facilities or changes in the region's natural conditions (Fazl Avali, 1998). Placing artificial recharge systems are one of the basic principles of creating these systems. The selection of sites based on scientific and natural points plays a critical role in the success and efficiency of the development of these systems to achieve the relevant goals. This process must be undertaken with considerable care. Identifying artificial recharge areas and substrates can be accomplished using various methods and parameters. No matter the method used, the results from different studies must be analyzed jointly, and then the most appropriate area for the study must be determined. Due to the presence of various characteristics in location, continuous changes of influential factors, and the need to examine the evaluated criteria, the use of GIS due to special features and capabilities, can be beneficial to this endeavor. The multi-criteria analysis method has been mentioned as a valuable model for integrating information layers in artificial recharge. Numerous studies have been conducted to locate recharging sites for artificial recharge.
Ramalingam and Santhakumar (2002), using GIS and remote sensing techniques, investigated suitable artificial feeding areas in a state in India which considered geomorphological, geological, soil, slope, land use, runoff intensity, and groundwater depth. As part of the research conducted by Hekmatpour et al. (2007), areas of the Varamin plain that can be artificial recharge were identified through classification and layer combining in a GIS environment and using a decision support system to make decisions.

Management of irrigation networks has always been one of the most important issues in the agricultural sector, and the use of modern valves and structures for controlling and adjusting the water flow is very important in irrigation channels. Water level control structures are used in irrigation canals to imple-ment delivery methods (Naghaei and Monem 2013).
Gates are one of the most used water structures in distribution canals that are used to transport and deliver water to consumer or to control the flow rate or water level. Determining the relationship governor on these structures can improve the performance of open canals and therefore prevent water loss. Lopac gate as a water level adjustment structure has recently attracted attentions and its performance in applied and practical areas of irrigation channels in different countries is accepted. The gate can be opened along the flow direction and can regulate upstream water level for various dis-charges by adjusting the gate opening angle (Oad and Kinzli 2006). So far little studies have been done on these types of gates. Some studies have examined hydraulic conditions of the flow passing through rectangular Lopac gate and presented the discharge equation as well as its coefficient in free flow and submerged conditions. In the present study, an experimental investigation has been conducted on new type of Lopac gate called elliptical lopac gates. This type of gate, which is a combination of rectangular Lopac gates and elliptical sharp edges have good function in passage of rubbish, foliage of trees and sediments along with the flow. We constructed and installed an elliptical Lopac gate as well as a rectangular Lopac gate at the laboratory scale to control and compare performance of both types of gates. The test were conducted for 5 opening degrees and for 5 discharge. Then, discharge equations of the elliptical Lopac gate in free flow condition with the help of buckingham pi theorem were presented with appropriate precision of Mean Absolute Percentage Error (MAPE = 4.44%).Also, changes in the energy flow dissipation crossing of Elliptical Lopac gate and Rectangular Lopac gate were studied and compared.

Figs are one of the main horticultural products in Iran due to their high nutritional value, high yield and economic value, and resistance to adverse climatic conditions. About one million tons of figs are produced annually in the world, Iran is the fifth largest producer of this product in the world (FAO, 2018). In addition to the above, the agricultural sector in Iran, like many countries, is the main consumer of water from renewable water sources. But there are not exact information on the volume of irrigation applied water and water productivity of this product in Iran. Therefore, this study was conducted with the aim of measurement of applied water at field scale and evaluation of water productivity of figs orchards at selected provinces in Iran.