فصلنامه علوم و مهندسی آبیاری
سال چهل و چهارم شماره 3 (پاییز 1400)

The irrigated cultivation of agricultural production is believed to be the country's largest consumer of freshwater resources, and the fact that Iran is located in arid and semiarid regions on Earth, the need for water for agricultural production is high. For this reason, more than 90 % of water resources are dedicated to the agricultural sector. However, in recent years, with the irregular and unsystematic spread of farming in the country, to meet the food demand of the growing population of the country, and the consecutive and severe droughts, leading to reduced rainfall, have caused loss of irrigation water and followed by drought stress for agricultural products. More than 45% of the farmlands are prone to dryness, and 38% of the world's population lives in these places. Therefore, in the future, most efforts will be made to produce more products in drought conditions. In other words, more crops should be produced per drop of water. Lack of water (usually called drought) could be defined as the lack of necessary and sufficient moisture for plants to grow normal with a complete life cycle (Fotoohie Ghazvini et al. 2011). Cucumber is one of the important greenhouse vegetables in Iran and the world. This product, in Iran, has the largest area under cultivation in comparison with other greenhouse vegetables; moreover, according to the 2009 statistics of the office of herbs, vegetables, and ornamental plants of the Ministry of Agriculture, the greenhouse cucumbers area under cultivation in Iran is 4701 ha. Cucumber is the product of warm and temperate seasons (with mild winters) and is very sensitive to adverse environmental conditions, and even rare changes in soil moisture content will have a significant adverse effect on its growth and yield (An and Liang 2013). Therefore, to study the effect of sawdust and water stress on the yield of greenhouse cucumber (Cucumis sativus L). The experiment was conducted in a complete randomized design with three replications.

Water stress is currently considered the most important and common cause of reduced yield in arid and semi-arid regions. Still, this tension may even occur in areas with high rainfall. Due to its resistance to drought and heat, Sesame is of great importance in developing agriculture in arid and semi-arid regions during summer planting. Sesame, with the scientific name Sesamum indicum L. is crucial in developing agriculture in arid and semi-arid regions during summer planting (Aien, 2013) due to its tolerance to drought stress and heat. According to the results of this study, the KC50662 and Oltan sesame varieties in terms of yield and yield components in normal conditions and stress were in the superior group. The two cultivars with higher stress tolerance index (STI) had higher performance in both conditions. Regression results for the STI index indicated that cultivars with higher STI had more seed weight per capsule and more capsules per plant (Abbasali et al., 2017). The results of one research showed that Olt cultivar with the highest levels of STI and the lowest SSI and TOL as tolerant cultivars were identified in normal condition and moisture stress conditions. The researchers also identified the Sesame Oltan variety as having the highest amount of STI and the least amount of SSI and TOL indices as a drought-tolerant (Molaei et al., 2012). In one study, Darab 14 sesame variety was superior in the normal conditions and moisture stress in terms of tolerance and sensitivity and was introduced as an outstanding cultivar in evaluating MP, TOL, SSI, HARM, and STI indices (Amani et al. 2012). Considering the importance of Sesame as one of the leading products of feed oil supply in Iran, the implementation of low irrigation can be adapted to the occurrence of droughts with water shortages. This study aimed to investigate the effect of drought stress on different levels of drip irrigation and the identification of superior cultivars based on drought stress indices.

More efficient decisions in groundwater problems can be improved by increasing modeling accuracy. The mesh-free numerical model is a way to achieve this goal. In recent years, various mesh-free methods for modeling groundwater have been developed. This paper aims to develop groundwater models by mesh-free methods, including Analytical Element Method (AEM) and Point Collocation Method (PCM). The AEM is an idealistic perception of the linear superposition concept (Strack, 1987). The PCM uses a set of points scattered within the domain of the problem that transforms the governing partial differential equations into algebraic equation systems and does not need any predefined mesh (Liu & Gu, 2005).

Astaneh-Kuchesfahan plain is one of the agricultural centers in the province of Gilan located between Tehran and the southern basin of the Caspian Sea in the north part of Iran. The geographical location of the Astaneh-Kouchesfahan aquifer is shown in Fig. (1).In this research, analytic element and point collocation mesh-free methods are used for groundwater modeling. The analytical element method is essentially a version of the superposition techniques. This method uses the exact analytical functions, and it doesn't need mesh-dependent interpolation functions (Fitts, 2012 ). Some points are distributed on the computational domain in the point collocation method, and the shape functions are created to solve the governing equation. This method is used to solve many partial differential equations with boundary conditions (Liu & Gu, 2005). The flow models are applied for groundwater modeling of the Astaneh-Kouchesfahan aquifer, and their results are compared. Particles Swarm Optimization (PSO) algorithm is used for the calibration of flow models. The models are developed by Python Object-Oriented Programming (OOP) language. The results of the AEM flow model based on the equipotential contour lines are shown in Fig. (2). Figure (3) also shows the nodal arrangement in the problem domain for the PCM model and geometry of the support domain.

Water is an important factor in the economic development of any country. Therefore, it is necessary to plan for optimal use of water resources and economic allocation of this resource for different uses (Tajrishi & Abrishamchi, 2004). Over the past decades, the increasing use of water resources and the low efficiency of its consumption have caused many environmental concerns. Water markets are an economic instrument that can be used to increase decentralization, optimize the allocation of water resources among consumers, and reduce the effects of water scarcity. Accordingly, water markets are mainly characterized by their capability to reallocate water for different uses so that this allocation is welcomed by those who designate higher potential values of water and naturally, derive more rational utilization of water resources in their own consumption (Badie Barzin et al., 2018). Given the importance of water, our research objective was to assess the effects of local and regional water markets in the Torshiz region. Data were collected without sampling at the level of cultivating certain crops including agricultural production, production costs, and inputs. Crop prices were provided by the Agricultural Jihad Organization of Khorasan Razavi Province, and the data on the demanded water products and all available water resources were provided by the District Water Company of Khorasan Razavi province. Howitt et al. (2015) studied the effects of drought on agricultural production in different parts of California and evaluated the role of local water markets in this area. The results showed that drought had a negative effect on not only the volume of surface water resources but also the depth of the groundwater supply and that the farmers were faced with inadequate water inputs. In this regard, the creation of local and regional water markets to balance water supply and demand has significantly reduced the effects of droughts. Additionally, the demand for irrigation water can be a good approach to cope with the effects of droughts. For this purpose, the present study mainly aims to investigate and evaluate the effects of the development of local and regional water markets in the Torshiz area and assess the potential of irrigation water transfers under drought and dehydration in the province's cities (as water conveyor region).

Meteorological drought is defined as a lack of rainfall over long periods, which reduces soil moisture and river flow. One of the critical drought assessment tools is drought indices (Tsakiris & Vangelis, 2005). So far, many drought indicators have been developed by researchers, for example, the RDI )Reconnaissance Drought Index) (Tsakiris & Vangelis, 2005). The difference between this index and other drought indices is that it is estimated based on two variables of precipitation and potential evapotranspiration. For this reason, it is more accurate than indices that are calculated only based on precipitation. So far, some studies have been used the RDI for drought assessment. Zarei et al. (2016) studied the spatial pattern of drought using the RDI index in southern Iran. The results showed that the area with dry conditions had an increasing trend. Asadi Zarch (2017) investigated the drought trend in Yazd province between 1966-2009 using the RDI index. The results showed that drought occurrence in Yazd increased during the studied period. Because, unlike other natural disasters, it is difficult to accurately determine the onset and the end of the drought period (Moried et al., 2005). Accordingly, it is difficult to diagnose and evaluate the drought phenomenon. Therefore, monitoring and predicting drought is very important in water resources management. The use of wavelets is a new and very effective way of analyzing signals and time series. Application of Wavelet in Wavelet- Artificial Neural Network (WANN) models as a function for training has recently been used as an alternative for Artificial Neural Network (ANN) models. In recent years, the combination of wavelet theory and artificial neural networks has led to the development of wavelet neural networks (Thuillard, 2000). Zhang et al. (2017) applied the ARIMA, ANN, WANN, and Support Vector Regression (SVR) models to predict droughts in China's northern Haihe River basin using the SPI index. The results showed that the WANN model performed better than other considered models for predicting the SPI values at 6 and 12 months time scales. This study aimed to predict the meteorological droughts in the Kuhrang region using ANN and WANN models. To this end, the efficiency of ANN and WANN models in predicting precipitation and potential evapotranspiration will be evaluated. Then, the Resilience Drought Index (RDI) will be calculated based on the predicted values by ANN and WANN to describe and prediction of Kuhrang wetness conditions.

Water is one of the sources that play an essential role in crop production and, if not properly managed, creates a severe limitation on drinking water consumption and agriculture. Water scarcity has become a crisis in recent years. It has challenged rice production in the country, so there is no choice but to increase productivity and optimize low-quality water. The use of effluent in supplying part or all of the water and nutrient needs of the crop, in addition to reducing the pressure on available water resources, also lowers production costs. It also avoids the problems of disposal of natural resources and environmental issues. Wastewater application can increase the amount of water available to the plant by changing the physical properties of the soil. Therefore, overall, these factors contribute to the sustainable use of water and soil resources in agriculture (Nikbakht & Rezaei, 2016). Direct and unmanaged use of this type of water, referred to as abnormal water, causes soil damage and reduces crop production in irrigation operations. Due to the importance of water and its scarcity in the country, proper use of water resources and irrigation water is one of the most critical goals in the agricultural sector. Therefore, a method that can increase the plant's yield under normal conditions by using a certain amount of water and the use of irrigation water in such a way that no problems occur for the plant can be used as a solution. It is essential to manage irrigation water use. In this regard, one of the approaches used in irrigation operations in recent years to use unusual waters is to pass irrigation water through a magnetic field. Water is a magnetic magnet that passes through a device with a magnetic core (Bodnarenko & Gac, 1984). Special measures, including unconventional water, are required to provide irrigation water for strategic products such as rice, which needs much water. Despite the beneficial aspects of urban wastewater, using these waters without proper management in agriculture leads to irreparable damage in a long time. To reduce its effects and the use of wastewater treatment systems, the magnetization method is considered. In the present study, the effect of magnetization of Gorgan urban wastewater effluent on hulls yield, biological yield, harvest index, water use efficiency, physical efficiency of water, and economic efficiency of water have been investigated.

Obstacles such as piers of a bridge inflow confuse and disturb its natural form. With passing the flow through these obstacle disturbances create downstream, called the Von Karman Street vortex shedding. When the frequency of the microwaves is equal to the natural frequency of the current approach, the resonance will form. If the flow walls are constant such as a flume, this phenomenon may see as a transversal wave. Actual examples of this phenomenon created near the bridge piers in a canal called the Delta Mendota, as well as in the New York canal around the I-84 Bridge (Schuster, 1967).Numerous people in this field have done research that mostly with variables such as channel width, shape, and placement of obstacles in the channel to study different wave characteristics, including its amplitude and frequency. Zima, L., and Ackermann (2002), Ghomeshi et al. (2007), Jafari et al. (2010), Meile et al. (2011), and Sarkar (2012) tried to find the maximum amplitude of the created wave by using obstacles with different diameters. Zhao et a. (2014) performed their experiments to measure the coefficient and tensile force created in the vicinity of obstacles while transmitting transverse waves. This study aimed to find a relationship between the percentage of obstacle immersion and wave characteristics.

Water scarcity has become a major constraint for the growth of societies in the world over the last few decades. The agricultural sector, as the largest water user, is prioritizing the optimal and sustainable allocation of water resources. In the present study, an optimization model was developed to maximize the profit and minimize the stability of water resources in the main canal and grade 1 and 2 channels in the irrigation and drainage network of Qazvin plain (Figure 1). The optimization model was proposed using a multi-objective genetic algorithm with two separate objective functions. In order to study the model farm, the major and important plants with their culture ratio in L1, L2, L3, L4, L4A, L5, L6, L7, L8, L9, L10, L20 canals in Qazvin plain, cost production and sales price of products were collected in the year 1394. The results of the optimization exercise indicate a 64% increase in net profit compared to the existing cropping pattern by reducing the level of cropping of products with low net profit and increasing the level of high-yielding products. On the other hand, according to the coefficients applied to water quotas, the definition of the second target function has reduced water consumption by optimal conditions from 100% of the water quota to 80%.

Gully erosion causes a drop in the channel bed, widening the channel and transporting a large amount of sediment downstream. Understanding the effects of various factors such as soil consolidation and the placement of the sandy layer on sediment transport rate are the goals of this research. Therefore, five samples of cohesive soils with various percent of clay and silt with short- and long-term consolidation were tested under natural conditions. Moreover, in one test, a sandy layer was laid on the gully bed to study the effects of this layer. Results indicated gully migration to upstream occurred at angles closer to 90 degrees when the percent of clay was raised. The same reduction in clay amount in long- and short-term consolidation caused the total gully migration and amounts of sediment to increase 2.5 times in long-term compared to short-term consolidation. The effect of clay reduction was more pronounced in the sample with long-term consolidation.

One of the bottlenecks in today's world is the lack of water for various uses; drinking, industry, agriculture, and environmental needs. The agricultural sector is the largest consumer of water, so it will be the first part which will be damaged by the water crisis. Therefore using methods that increase water productivity or, in other words, increase yield production per unit volume of water is essential. Deficit irrigation is a low cost and simple method for this goal. This research was carried out in order to investigate the effect of deficit irrigation and alternate furrow Irrigation on yield and water productivity of Maize in Khorramabad climate.

The treatments consisted of conventional irrigation with 100% water requirement (I100), regulated deficit irrigation with supply of 80% of plant water requirement (DI80), regulated deficit irrigation by applying 60% of plant water requirement (DI60) and using partial root-zone drying (PRD), which was conducted in plots of 18 square meters in a complete randomized block design with three replications at the Research Farm of Faculty of Agriculture and Natural Resources, Lorestan University. The irrigation system of the farm was surface furrow and delivered water to each plot through polyethylene pipes. The volume of water applied to each plot was measured by a volumetric counter.In this study, the net depth of irrigation was calculated by measuring soil moisture deficiency in the root zone relative to field capacity point. For this purpose, in the days before irrigation, soil samples were taken from the root of the plant in all three replications of control treatment and after weighing, they were placed in the oven and at 105 ° C for 24 hours. After drying, the samples were re-weighed and soil moisture content was determined. At the beginning of the growing season and until June 12, the same irrigation water was applied to all treatments until the plant was fully established and reached a 4 to 6 leaf stage. In fact, until the fifth irrigation, all experimental plots were irrigated equally. After this step and assurance of plant establishment, the research treatments were applied. For the treatment of deficit irrigation using partial root drying (PRD), the calculated water requirement based on 100% water supply was applied to half of the furrows. In the next irrigation event, the remained half was irrigated in the same way.