Journal of Irrigation Sciences and Engineering
Year:2018 | Volume:41 | Issue:1 |Papers Count:17

Scour around piers and abutments leads to a lot of bridge failures. Scouring around the bridge piers and abutments is one of the most important factors in bridge failure which happens over time and increases during floods, probably causing general damage to the bridge. Accordingly, the accurate estimation of scouring around the bridge piers and abutments can help engineers to take steps to deal with bridge destructions. Recently, data-driven models have been used widely to estimate the scour depth around bridge piers and abutments. Najafzadeh, Barani and Hessami-Kermani (2015) used a set of data-driven models such as the gravitational search algorithm and the particle swarm optimization algorithm to estimate the scour around bridge abutments. Sediment particles size, geometric characteristics of bridge abutment and approach flow conditions were considered as effective parameters on scouring mechanism. The results of this research showed that data-driven models can estimate the scour depth with high accuracy. In the present study, M5 tree model has been used to predict maximum scour depth around bridge abutment. High accuracy, simplicity and understandability are considered the advantages of this algorithm. A huge amount of data from credible references have been used to build and validate the tree model...

Limited water resources and energy, low yield utilization of irrigation networks, increasing population and a growing need for these vital resources reveal the necessity of proper planning for optimum use of water resources. The cropping pattern has a major role in the design of irrigation and drainage networks. Ziaei et al. (2015) compared energy productivity of different crops (wheat and barley) in Sistan and Baluchestan province in Iran. Results showed that the amount of energy productivity for wheat and barley fields were 0. 056 and 0. 066, respectively. Barley production was more efficient from various aspects of energy consumption rather than wheat in the studied region. Adhikary et al. (2015) prioritized the commonly grown crops based on rainwater use efficiency and their comparative performance during water stress condition in India. Results showed that vegetable crops have higher rainwater use efficiency than cereals and pulses. Among the cereals, maize and finger millet performed better in upland areas while they did better in paddies in low lands. Igwe et al. (2015) examined optimum cropping patterns for selected root and tuber crop based production and resource allocation of smallholder farmers in Abia State, Nigeria, using the linear programming approach. They reported that farmers’ purchasing power would be enhanced given optimal crop production activity combination and land resource allocation. Singh et al. (2001) and Garg and Dadhich (2014) also studied on optimal cropping pattern in Pakistan and China, respectively. The present study was performed to determine the prioritization of cultivating major agricultural crops (wheat, maize, alfalfa and barley) in sprinkler irrigation systems under both subsidized and non-subsidized conditions with respect to energy and water costs using numerical taxonomy method...

When water resources are limited, the type of plant, growth stage and soil type should be considered for optimal water consumption. Also, it is necessary to calculate the reliable values of soil moisture content, moisture stress and yield function in order to apply deficit irrigation. Management of water consumption in agricultural sector, regardless of water, soil and plant relationships, requires time and cost. Therefore, models of water, soil and plant relationships have been developed due to the limitations of these experiments regarding farm conditions, the short duration of the experiment and the limited number of scenarios examined in the experiment. Optimal irrigation planning is one of the main factors in promoting water productivity and yield. Models such as the AquaCrop which simulate the effects of water levels on yield are useful tools for on-farm water use optimization. Alizadeh et al. (2010), with irrigation on wheat in Karaj on five treatments with 100, 80, 60, 40 and 20% water requirement as well as a single-irrigation treatment and evaluation of the Aquacrop model for these treatments, concluded that the model was efficient for predicting the amount of seed yield, plant evapotranspiration and water use for 7-day irrigation intervals. The model was, however, less efficient for 14-day irrigation intervals...

Water allocation in arid and semi-arid regions is considered a human challenge all around the world. The need for optimum utilization of water resources, especially in agricultural use, is very important. Agriculture, which uses the greatest percentage of most water resources, has also penetrated in human life and culture. The aim of this study is to provide an approach to allocate and optimize water use in Dez basin using WEAP model...

The AquaCrop model improves farm management practices, including plant density, planting time, and chemical fertilizers. It also simulates crop yield, soil water content, soil salinity, and water productivity. One of the applications of this model is the assessment of rainfed production during the long term, the effect of low fertilization, the productivity of real water on the farm, and the analysis of future climate scenarios. The disadvantages of this model include the lack of calibration of the amount and time of fertilization and the lack of consideration of plant diseases and weeds (Raes et al., 2009). The AquaCrop model is suitable for simulating different water and nitrogen managements on yield (Khoshravesh et al., 2012). Ebrahimi, Rezaverdinejad and Majnooni Heris (2015) evaluated the AquaCrop model under different irrigation and nitrogen fertilizer managements for estimating maize grain yield and biomass in Shiraz. This model predicted the grain yield of maize with high precision and biomass obtained in all treatments was more than the estimated values. Alishiri, Paknejad and Aghayari (2014) in simulating sugarbeet growth under different irrigation regimes and nitrogen fertilizer concluded that the highest error in performance simulation was in the treatment that had the highest fertilizer stress. The purpose of this study was to calibrate and validate the AquaCrop model for estimating the crop grain yield (GY) and biomass (B) of Canola under different irrigation regimes and pure nitrogen fertilizer levels in loamy soils in Gazvin, Iran, for two years...

Watermelon is one of the most important profitable vegetables in Khuzestan. A mild water stress helps watermelon to develop the root system. Water stress has a negative effect on the yield of watermelon but it increases the quality of the fruit. Watermelon is usually planted in mid-June and is irrigated in a furrow irrigation which, generally, has low application efficiency. The high amount of water consumption, especially in the early stages of growth, requires considering the drip irrigation method. Recently, using drip (tape) irrigation has become more common in Khuzestan. However, there is not enough information regarding the impact of pressurized irrigation systems on the performance of watermelon varieties. Therefore, the current research was conducted with the aim of evaluating tape irrigation levels on watermelon varieties in Northern Khouzestan...

draining the flood of enormous dams and transmitting the procedure to the downstream is one of the important issues regarding hydraulic structures. Plunge pools are the main structures to dissipate the high rate of energy. The amount of energy at an outlet jet depends on various parameters such as the dropping height, the thickness of the jet, and other environmental conditions. Local erosion in plunge pools with alluvial beds is a complex phenomenon and determining the geometric features of the scour hole is really difficult. The outlet flow mixes with the turbulence factor and hits the bed of the plunge pools with a semi-perpendicular condition. Therefore, the present study was conducted to determine the scour which was caused by inlet air along the middle water jet on the bottom of the plunge pools. Xu et al. (2004) tested the aeration effects on the scouring caused by the falling jet and obtained a small relationship between the percentage of air jet density and the relative scour depth. The results informed that aeration affects the shape of the scour hole and essentially reduces the scour depth. Manso et al. (2004) investigated the interaction of the geometric shape of the submerged pond with rocky bedding on the rate of diffusion of the falling jet. They tested various diameters of jets, 5. 5, 11 and 16. 5 times the diameter of falling jet, on the smooth and rough beds to investigate the dynamic pressures with frequencies between 1 to 2 KHZ. Their findings showed that the geometric shape of the pond has a direct impact on the jet diffusion rate. Duarte et al. (2015) studied the effects of air inlet to jet on the dynamical pressure on the floor of the submerged pond. They increased the jet's velocity to 22 m/s. The final results showed that the air inlet to the jet led to a decline in the total pressure on the floor of the pond...

Forage sorghum is one of the tolerant salinity plants that can provide a good source of forage under irrigated conditions with saline water. Considering the quality of the products, their value is estimated with regard to their quality. Therefore, similar to many crops, the quality of forage plants should be considered. The quality of forage can be a function of forage consumption and its digestibility(Paterson et al., 1994). Forage plants in livestock trapping as a result of livestock production are undeniable in the supply of human needs. Unfortunately, in Iran, less attention is paid to the production and management of forage compared to other crops. As a result, lack of attention to the quantitative and qualitative increase of forage has led to a shortage of meat and dairy products and a decrease in their quality. Therefore, paying attention to the cultivation of forage plants with a scientific method in a country that is faced with the excessive growth of population and the shortage of rich meadows is very important (Noroozi et al., 2015). Sorghum is one of the important forage crops that is widely cultivated as summer forage in most of the dry and semi-arid countries of the world. Forage sorghum is used as green, dry, silage, or even for direct grazing of livestock (Rezvani moghaddam and Nasir mahallati, 2004). In thecurrent research, the effect of drought stress on sorghum was investigated. The results showed that the yield components including the number of seeds per plant and weight of 100 seeds decreased compared to the control (Innes and Black, 2001). Therefore, in this study, the effect of different levels of salinity and irrigation water and harvest on the yield of forage sorghum was investigated in order to use the results for proper planning to increase agricultural production in specific conditions, i. e., salinity and water restriction...

flood control is one of the important requirements in development projects of major water resources. In this regard, the main purpose is to reduce or eliminate the economic, social and environmental damages that are caused by floods. On the other hand, many irrigation and drainage networks are in the vicinity of the rivers and, therefore, the occurrence of floods can cause irreparable damage to the land and network structure. Embankment failure due to water overtopping during floods is a common phenomenon which brings great financial losses, human casualties and environmental damages. Therefore, this research was aimed at investigating the mechanism as well as the effective variables on embankment failures...

Drought refers to a period of time when water shortage occurs and, therefore, the environment and human life are disrupted. Of course, depending on the regional considerations and the objectives of any research, drought can have different definitions since the lack of water in different regions is defined differently. Drought forecasting is almost impossible and is usually a phenomenon that progresses slowly. As a result, well-timed detection in the early stages makes it possible to reduce the adverse effects on different parts of the environment, agriculture, water resources, etc. Drought characteristics such as duration and severity can be determined by drought indices. Scientists have proposed various indexes to assess this phenomenon. Drought index is a useful tool to assess drought characteristics. Effective Drought Index (EDI) is a new methodwhich is based on the cumulative daily precipitation and uses a weighting method...

Insertion of different water structures such as bridge piers in the flow path contracts the flow cross section and causes backwater at upstream sections. The velocity and turbulence of flow increases around these structures and bed scouring will occur. To discover the effect of different structures in the vicinity of channel junctions on flow and sediment patterns, precise studies should be conducted. The effects of bridge pier on flow and sediment patterns in stright and curve open channels have been investigated (Salaheldin et al., 2004, Tabib zadeh et al., 2005). However, its effect on flow and sediment patterns at open channel confluences has rarely been studied...

Groundwater resources are known as one of the most important water resources. Proper knowledge and exploitation of groundwater, particularly in arid and semi-arid regions, plays an important role in sustainable development in different fields such as agricultural, social, and economic activities. Many models have been used in order to predict groundwater level including empirical time series models and physical models (Bierkens, 1998). It is true that these models have been widely used, but when the dynamic behavior of a hydrological system is changed during the time, the mentioned models may not be able to predict water resource parameters, therefore making them unsuitable (Nayak et al. 2006). On the other hand, physical models need a great deal data to simulate groundwater fluctuations and, since the relations among effective parameters may be nonlinear, the mentioned models are not practical enough to show the existing relations...

Using some additive materials to gypsum soil can increase its compressive strength and erosion and make it fit for civil projects in irrigation networks. In this study, (Journal No. 268., 2003) five levels of cement (5, 8, 10, 12 and 15 % to dry soil) and three levels of micro silica (0, 5 and 10 % cement) were added to the local soil. The processing of soil samples were conducted in two temperature (27 and 400C) and their compressive strength was studied and analyzed via SAS statistical software. In the present research, the best combination, with the minimum addition and a high compressive strength, was reached by adding 10% cement and 10% micro silica to the soil. In order to evaluate the sample’ s erosion potential, it was exposed to water jet plane in four angles (Ө = 0, 30, 60, 90), five speeds (V = 2, 4, 6, 8 and 8. 64 m/s) and three times (T =4, 8 and 12 hr) and the highest weight loss erosion (dw) was observed between the speed of 4 to 8 m/s and the time of 8 hours later in a horizontal state (0 Ө =)...

Water erosion causes serious damage to all natural ecosystems, including the soil and nutrients loss (Collman et al., 2010). Nutrients loss and soil fertility reduction are the most important effects of soil erosion, which increase the fertility of soils in downward of the basin and cause contamination of surface and underground water (Telles et al., 2013). Soil loss is a serious problem in developing countries and has been a source of concern (Wolancho, 2012). Phosphorus and potassium are important elements in agricultural products. Each of the mentioned elements has especial behavior in transferring by runoff. Potassium is very mobile in comparison with phosphorus, so it is easily displaced by water from the runoff process. Despite numerous studies done in the world regarding the loss of elements in runoff and sediment, there is no accurate information in this regard in Iran. In Lorestan Province, due to the lack of attention to land suitability in land uses, basins are severely subject to erosion and soil degradation. Therefore, the present study was conducted to investigate the effects of slope and type of land use on the loss of potassium and phosphorus in runoff in Kakasharaf Basin in Lorestan province...

To calculate the wind shelter index (Sx) for points in a region, the wind shelter index values are calculated for each set of points in different lengths and directions. Among these lengths, the length of the Sx corresponding to it has the highest wind shelter and is known as an effective length. Winstral et al. (2002), Winstral and Marks (2002), Erickson et al. (2005), Molotch et al. (2005), Molotch and Bales (2006), Sharifi et al. (2007), Litaor et al. (2008), Tabari et al. (2009) and Maroufi el al. (2010) in order to determine the effective length in snowy areas inevitably used the correlation of Sx values for each desired length and depth of snow. Winstral et al. (2009) in study of wind speed distribution methods determined the effective length by establishing the relationship between the difference in the values of the Sx and the difference in the velocity of the wind. Farokhzadeh et al. (2014) also succeeded in determining the effective length by examining the correlation between a parameter named average wind shelter slope and Sx, provided that the selected points were in wind conditions. Therefore, due to the limitation in the method proposed by Farokhzadeh et al. (2014) for calculating the Sx in non-snow areas such as lake levels, the use of a specific type of algorithm for determining the effective wind shelter length seems necessary (Shahi, 2017). Therefore, in this study, according to the existing conditions, a method was proposed for selecting the effective length of the shelter...