Journal of Irrigation Sciences and Engineering
Year:2019 | Volume:41 | Issue:4 |Papers Count:20

Recently, the phenomenon of climate change, drought, the exploitation of the ground water has caused a sharp decline in groundwater levels, which has also led to groundwater related subsidence and desertification. Therefore, reliable prediction of groundwater level for managing these resources is of prime importance. Nowadays wavelet transforms through signal decomposition to time and frequency has created an exceptional method for signal processing, with the help of the transformation of the wavelet that has the ability to split the time series into a multi-dimensional substrate with different scales. One of the useful characteristics of wavelet transforms is the filtering algorithm, which divids the data into two groups of approximation and details by passing them through the wavelet filter. In this study, monthly groundwater surface, rainfall, and temperature data were used. Using the program code written in MATLAB software, it is necessary to analyze the time series data of all three parameters of temperature, precipitation, and water level. The values of the parameters were selected as inputs and placed in the wavelet function. For analyzing all the parameters, according to various mother-wavelet experiments, and considering the above mentioned point, five motherwavelets (Haar, Coif, Symlet, Db, Db4) were selected. For this purpose, the program was first implemented for each of the following wavelets with 4 different decomposition levels. After several software runs under specific conditions and scenarios and then comparing them with each other, results were obtained...

In general, the energy dissipating structures are used in order to prevent the destructive effects of high flow velocities through the spillways. Among these structures, the most commonly used structures are chutes in water conveyance systems in dams, irrigation and drainage networks, alluvial rivers and wastewater collecting and disposal systems. The energy dissipating structures are used at the downstream of this systems. The advantage of this method to the previous methods such as stepped spillway is that the risk of cavitation is less and it is more economical. One of the ways to reduce the size or eliminate low energy dissipating structures is to use methods for reducing the flow energy over the chutes. One of these techniques, which has been used so far, is to create steps over the spillway. Another method is the application of obstruction or roughness on the spillway’ s bottom. Baffled chute is a type of the dissipaters that is used extensively in open drainage networks and where the tailwater level has large fluctuations. The significance of this type of energy loss becomes more evident where the tailwater has obvious fluctuations. The purpose of this study is to numerically simulate the effect of cylindrical baffles over the chutes on the energy dissipation magnitude. In particular, the purpose of this study is to determine whether the cylindrical baffles can effectively reduce the kinetic energy and reduce the dimensions of the stilling basin...

Meandering river bend migration is a common phenomenon which destroys agricultural lands and civil infrastructures around the river. The main cause of such migration is due to developing a secondary flow within the bend in which a helicoidally circulation is developed and as a results the scour hole at the outer bank toe is created which causes collapse of the outer bank and its migration. Over the last decade many countermeasures against such scour have been developed. These measures modify the flow within the bend redistribute the local bed shear stress for the purpose of reducing the toe bank scour. Triangular vanes are one of such structures that help stabilize the outer bank by modifying the flow pattern in the river bend to prevent the scouring of the outer bank. Triangular vanes have been studied successfully by Bhuiyan et al. (2010) in a sinuosity river path and in a 90 degree flume bend by Bahrami-Yarahmadi and Shafai Bejestan (2016). Based on these studies this measure, if designed properly, not only can shift the scour from the outer bank toe to the middle of the river, it transport sediment to the downstream of the vane and deposited in between the vanes which create a new bank. The structure has been defined environment friendly since it create an environment suitable for aquatic animals. The aim of the present study is to investigate the application of triangular vanes in a 180 degrees of Jangiyeh bend in Karoon River south of Ahvaz and to determine the bets distance for installing the vanes.

Wetlands are the intermediate lands between drought and aquatic ecosystems and are the most fertile and most productive ecosystems on earth (Germandy et al., 2008). Management of wetlands for conservation includes the conservation of wetlands from direct human pressures and the maintenance of natural processes in the vicinity of wetland. Monitoring the changes in wetlands and their surrounding lands can be useful for managing these valuable ecosystems (Sabzghabaei et al., 2015). In order to better protect the sustainable development, the necessity of differentiation and recognition of the characteristics of wetlands makes it possible to determine the resources, source of origin, location and factors of their destruction, so that they can be managed with a proper understanding of them. (Lambin and Gist, 2006). If society wants sustainable development in the first stage, we must acquire a complete knowledge of our environment, and in the second stage we must work with strategic planning to maintain it (Jafari, 2015). Strategic planning models are unlimited, but almost all of them are inspired by the SWOT analytical model (Chang and Huang, 2006). From the perspective of this model, an effective strategy will maximize strengths and opportunities and minimize the weaknesses and threats (Ganjali et al., 2014). Hour_ Al_ Azim wetland is located in the common border region of Iran and Iraq in the southwest of Iran and in the county of Dashte Azadegan of Khuzestan province (Behroozirad, 2008). Over the past decade, due to the intensification of human activities, in particular the development of the Azadegan oilfield and the pressures of human societies on the studied wetland, there have been profound changes in the region. This research was conducted with the aim of developing appropriate conservation strategies for Hour_ Al_ Azim wetland...

In recent years, human activities induced increases in atmospheric carbon dioxide (CO2) which caused global warming and climate change. Climate change is anticipated to cause negative and adverse impacts on water systems throughout the world. Higher temperatures are expected to lead to a host of problems. These include melting snowpack, altering both the intensity and frequency of precipitation, increasing evapotranspiration and else. (Delghandi, 2016). Reference evapotranspiration (ETo) is a key hydrological variable quantifying a major water loss from catchments and basins, which can be used to calculate actual evapotranspiration (ETa), scheduled irrigation and prepare input data for hydrological models. The irrigation water requirement basically represents the difference between the crop water requirement and effective precipitation. The only factors affecting ETo are climatic parameters as water is abundantly available at the reference evapotranspiring surface (Allen et al., 1998). The first of climatic parameters is air temperature. As temperature increases, evapotranspiration also goes up. Some study conducted to indicate climate change impact on ET (e. g, Behmanesh et al., 2015; Sheidaeian et al., 2015; Babaeian and Kouhi, 2012). In this study, climate change impacts on reference evapotranspiration (ETo) and precipitation deficit (PD) were studied from 2010 to 2099 in Semnan region. The objective of this study was to examine the climate change impact on the ETo regarding the uncertainty of Atmosphere-Ocean General Circulation Models (AOGCM) and Greenhouse Gases Emission (GHG) scenarios...

Studies have shown that the global climate has been dramatically changed during last decades. The results of the investigations have shown that enhancement of greenhouse gases due to human activities is one of the main factors of climate change in the present century. CO2 is one of the most important greenhouse gases, which has begun to increase rapidly since the mid-19th century. Studies have shown that carbon dioxide concentrations have risen by about 43% from 277-280 ppm since the late 1700s and now the concentration of this gas is close to 400 ppm (Samenow, 2013). According to scientists, carbon dioxide is responsible for 61% of the total global warming. In addition to the harmful effects of increasing the carbon dioxide concentration and global warming, this gas has a positive effect on agriculture, which increases its importance. The results of the research indicate that increasing CO2 concentration causes photosynthesis enhancement also by increasing the photosynthesis dry matter weight increase, and consequently the amount of production increases (Semenow et al., 2012 ). Rogers et al., (1994), indicated that doubling carbon dioxide concentration has led to an increase in plants’ yield approximately by 33%. In addition, environmental conditions such as light, temperature, water and available nutrients, moisture, etc., and the interaction between them, overwhelms the effect of plants on changes in carbon dioxide concentration...

Drought is a natural phenomenon that causes water resources shortage in various sectors such as drinking water, industry and agriculture. Drought is one of the climatic phenomena that can be observed not only in arid and semi-arid regions, but also alternately in wet areas. It should be noted that aridity and drought are different, aridity is a climatic trait specific to arid and semi-arid regions and is a permanent feature of the climate of the dry region (Eslamian et al, 2012). Liu et al (2011) with the study of meteorological and hydrological droughts in Oklahoma State discovered the two-day drought incidence of 2 months and the correlation coefficient between SPI and SDI profiles in an optimal state was 0. 63. Eskandari-Damaneh (2015) investigated temporal and spatial relationships between meteorological and hydrological droughts in Tehran province. The results showed a correlation of 99% between meteorological and hydrological droughts and the increasing trend of drought in Tehran province. Mahmoudi et al. (2015) assessed the drought of meteorology in Sistan and Baluchestan Province using a standard score index and its impact on water quality in the province. Delpla et al (2009) examined the impact of climate change on the quality of surface waters in relation to drinking water production and concluded that climate change has reduced the quality of drinking water that has potential health impacts. Also, Mosley (2015) indicated that drought increased salinity, algae and soluble ions, which greatly reduced the quality of freshwater. According to drought studies, the main objective of this study is to study the drought of meteorology and hydrology, as well as to determine the probable delay between the occurrence of these two types of drought and their impact on river water quality, for water resources management in Godarkhosh basin which is one of the most important basins in Ilam province...

Regulated Deficit Irrigation (RDI) is the strategy of reducing irrigation rates, during a specific period of growth and development, with the objective of conserving water and managing plant growth while maintaining or improving yield and quality. Partial root zone drying (PRD) is a possible irrigation technique that deliberately exposes the plant to water deficits to induce physiological responses that can improve the efficiency of water use. It involves irrigating only one part of the root zone in each irrigation event, leaving another part to dry to certain soil water content before rewetting by shifting irrigation to the dry side. Various plants are different in economic efficiency of irrigation water used. Medicinal plants, as a collection of plants with high economic value, can produce more capital than other plants in terms of water scarcity. The objective of this study was to determine the response of peppermint yield components, oil yield, and water use efficiency to regulated deficit irrigation and partial root-zone drying in field condition...

It is necessary to coincide the conditions and specifications of field with the characteristics of the irrigation systems. Feasibility and investigation of the most susceptible regions for implementation of different irrigation systems according to water quantity and quality have great importance and prevent energy and capital resources losses. Different effective variables in selecting irrigation systems types cause that various regions have different potential in water harvesting. Due to different parameters have a different effect on the selection of the suitable location for water harvesting, each element needs to be weighed based on its importance degree. For this purpose, the analytical hierarchy process (AHP) (Saaty, 1980) is used. By combining this method with GIS, multi-criteria decision making is possible at large and high precision levels. In this research, the possibility of implantation of different irrigation systems (surface, sprinkler and drip systems) was evaluated using the fuzzy analytical hierarchy process method (FAHP) based on the quantity and quality of groundwater in Miandoab plain...

Rainfall-runoff is one of the most complicated hydrological processes that is affected by various physical and hydrological variables. Therefore, understanding and predicting runoff formation processes and their transfer to the outlet point of the watershed is one of the most important issues of hydrological sciences (Salajegheh et al., 2009). Botsis et al., (2011) simulated daily rainfall-runoff of a catchment in the California, USA. They compared the performance of SVM with three types of kernel function with ANN. Finally, the SVM had a more accurate simulation of rainfall-runoff. Nourani et al., (2009) applied the hybrid of wavelet-ANN to model rainfall-runoff of Lighvan-Chay basin in Iran. The results showed that the proposed model is capable to predict long-term and short-term rainfall events due to the use of the time series with multiple scales as input layer of ANN. Darreh-rud river as the most important branch of Aras border region in Iran, is one of the main rivers of Ardabil province and the main source of water supply in different parts of the province. On the other hand, the Emarat reservoir dam is under construction on the river. Therefore, ANN, WNN, GEP and LS-SVM models were evaluated for estimating the inflow of Emarat dam (located on Darreh-rud river, Ardabil province)...

Water passage from steep slopes in river engineering issues and the design of water transfer structures is inevitable. Because of the steep slope of the surface, the surface velocity and surface erosion rates are high. Energy control in high-speed flows is one of the challenges of designing hydraulic structures. These flows, for example, occur in places such as dam overhead structures, drainage systems of urban areas and Mountain Rivers with a steep slope. One of the ways to reduce dimensions or eliminate energy depreciating structures is to use methods to reduce the kinetic energy of flow over the weir, including using of stairs or blocks on the overflow. The use of large-sized stairs or blocks will cause the passing jets of flow to be separated and as a result turbulent, which can effectively deplete the kinetic energy of the current. The problem with using a staircase or block is a huge cost of built and a high risk of cavitation. Another method of energy depreciation is to apply roughness at the overflow bed, which may be an efficient way to reduce energy. Roughness can dramatically reduce the flow turbulence, and thus reduces the risk of cavitation. Also, roughness can reduce the flow power over the overflow and reduce the depth of the lower erosion pit by removing or reducing the dimensions of the relaxation basin. Most studies in this field have investigated the effect of these roughs on the amount of energy depletion, which in addition to energy depletion is also important for lowering the erosion of the structure. However, for the economic design of hydraulic structures, designers need to have full knowledge of the particle mechanics and the dimensions of the scour hole, so that they can consider the requirements for the stability of the structure, which has so far been investigated insufficiently. Therefore, the present study aimed to investigate the effect of roughness density on sloped bed surface on its downstream scour depth...

As the population grows and people's living standards rise, the global demand for freshwater is constantly increasing. Agriculture is not only the largest consumer of water in the world, but also one of the cheapest and least efficient consumers with the highest subsidy rates. Nowadays, optimal management of irrigation water is very essential issue and valuable tools calls irrigation management models to improve for this optimizing and Facilitating. For this purpose, the two-year 2004-2005 & 2005-2006 experiment to determine the accuracy of the simulation AquaCrop model calibration and AquaCrop indices barley crop was in Darab-IRAN. Many countries, especially those located in arid and semi-arid areas, need water to produce agricultural products, and many of our country's crops and gardens are also cultivated in the water...

Protection of water pipelines-wastewater or fuel materials-on the bed of erosion of the sea and rivers against such factors as bending, slipping and even fracture are important and costly issues in ocean engineering. In order to protect the potential destruction and fracture of these pipelines due to hydrodynamic forces of flow-waves or human activities. It is necessary to be covered with a concrete-coat or buried at an appropriate depth of bed with trenching. Objective observations showed that the pipelines that are located on the erosion bed of the sea and the rivers have the potential to produce a natural burial (self-burial pipe) in a bed of sediment, due to localized scouring. But in natural conditions, the burial process takes place with little speed. Therefore, by installing the spoiler on the pipelines, it is attempting to increase the Perpendicular cross-section of the flow (making changes in the pattern of flow around the pipeline) and, finally, the occurrence of erosion and self-burial inlower environmental velocities, but more intense. Therefore, it is necessary to first investigate the factors affecting for erosion sediment bed and estimate the dimensions of scour hole under pipelines, to study the accelerating factors and its effects on ocean engineering...

Seepage reduction in earth canals is a practical way for maintaining available water resources. The use of proper and inexpensive materials is a practical way for decreasing seepage losses in canals. Experiments showed that seepage in small channels and field canals is usually more than conveyance canals. One of the most important factors for determining seepage rate is permeability of constituent materials of bed and sidewall of canal, which depends on porosity size. Smaller porosity size results in less permeability, which is proportion to squared diameter of the porosity USBR (1963). Garg and Chawla (1970) showed the seepage rate is high in unlined canals. Aylward and Newton (2006) determined water losses rate to be 25% in an earth canal with 82 km length and found water losses volume to be 11. 9 million cubic meter along a period of 210 days of irrigation season. The results showed that water losses decreased by 30% through 45% by controlling seepage and also water losses in the canal are directly proportional to permeability. The purpose of this research is to introduce an economic lining in order to reduce seepage losses of four-degree irrigation canals and increase their water conveyance efficiency. Hence, it is recommended to use sodium carbonate and sugarcane and sugar beet factory waste instead of use of heavy machinery for compacting of soil...

Plastic pipes are widely used in pressurized water systems. The analysis of transient flow and estimation of maximum and minimum pressure wave propagation in pipeline and pipe networks is required for design and practice of piping systems, pumping stations, and dam water conveyance tunnels. The viscoelastic properties of the polyethylene pipes have significant effect on the estimation of pressure wave speed and attenuation in transient flow. The use of polymeric pipes such as polyethylene and polyvinyl chloride has recently increased due to their technical and economic advantages over steel and concrete pipes. Due to viscoelastic behavior, polymeric pipes have a significant impact on transient flows (Pezzinga, 2002). In a fast transient flow event like water hammer, viscoelastic properties of polymeric materials cause a residual stress in the pipe wall. These deformations will not return to their original state immediately after unloading (Covas, 2003). This viscoelastic behavior also affects the intensity, shape, and dampening of pressure oscillation in transient flows. Covas (2003) developed a numerical model to simulate the viscoelastic behavior of the pipe wall in transient flow events. In this study, the results of a linear viscoelastic model were compared with experimental results in the presence and absence of unsteady friction loss. Soares et al., (2008) also considered transient flow in PVC pipes, and their results were in good agreement with those obtained by Ramos et al. (2004). Evangelista et al., (2015) studied water hammer phenomenon in a Y-shaped system both experimentally and numerically. According to their results, the linear viscoelastic model was able to simulate the water hammer phenomenon in this system...