Iranian Water Research Journal

Abstract Study of open-channel turbulent flow over rough bed is beneficial to provide a better understanding of many riverine physical processes. Indeed, the knowledge of rough bed turbulent flow has a significant effect on sustainable environmental management of the mountainous rivers.
The structure of rough bed turbulent boundary layer in inner region is affected by bed geometry in addition to flow characteristics (e.g. viscosity). Presence of rough elements in the channel bottom makes differences between boundary layer flow over the smooth and rough beds. Presence of roughness enhances the secondary currents. The secondary currents’ enhancement can play an important role in sediments’ transversal and longitudinal transport. The secondary currents’ formation in rectangular open-channels is attributed to the side wall effects. If the channel width is small, i.e., the side walls are not too far from each other, the secondary currents are formed in whole cross-section. Accordingly, based on the channel aspect ratio (which is defined as the ratio of channel width to the water depth; i.e. B?H), Nezu and Nakagawa [14] classified the rectangular open-channels: First class is called narrow channels which has an aspect ratio smaller than 5. In narrow channels, the secondary currents are present in whole cross-section. The second class is wide channels where B?H is larger than 2.5~5. In this category, no secondary currents are formed in the channel central part (i.e. y?(H>2.5) where y is transversal location) and so flow characteristics do not noticeably undulate in the lateral direction. Despite many studies about narrow channels, only a few number of studies deal with secondary current presence of absence and also their characteristics in wide channels.
This paper deals with turbulent flow hydraulic characteristics in straight open channel under the roughness elements’ effects, with high aspect ratio (i.e. wide channel). More precisely, in this paper, characteristics of the flow due to formation of secondary currents in the rough bed condition are studied. For this purpose a series of laboratory measurements using ADV probe were conducted which will be explained in the following section.
The laboratory experiments were conducted in a straight rectangular flume, 11 m long and 1 m wide, at the Hydraulic Laboratory of Tarbiat Mo‌dares University. The channel side walls and bed were made from glass and smooth Per‌spex, respectively. Free surface profiles were measured with an ultrasonic distance transducer to control the flow uniformity condition. Small surface waves at the flume entrance were eliminated using a 1.5 m long and 0.95 m wide polystyrene plate held parallel to the upper water surface just at the end of the water intake. The flow rate was controlled with a gate valve and was measured using a magnetic flow meter. During experiments, four different hydraulic scenarios were performed in subcritical flow condition. A summary of the experimental conditions is reported in Table 1. Also, the rough bed characteristics during the measurements are reported in Table 2.
Flow field was measured by a vectorino type 10 MHz down looking micro- Acoustic Doppler Velocimeter (ADV) capable of meas‌uring instantaneous three velocity components. The velocity measurements were done at a sampling rate of 100 Hz over a 45 mm3 sampling volume. Each velocity point was sampled for at least 300 s in order to assure that the number of independent samples is enough for statistical analysis. In normal- and span-wise directions, distance between two consecutive measurement points were 5 cm and 5 mm, respectively. Measurements were performed in just half of the channel, after verifying symmetry of the velocity distribution with respect to the channel centerline. In addition to the flow field, the local bed shear stresses were measured using a homemade Preston tube named three-tube device in the present study. The manufactured probes were connected to four capacitive types, the Keller 41X pressure transducers using silicon tubes and so the collected data could be stored in the computer. Each point measurement with three tube pressure instrument was continued for around 300 s similar to the measurement of the velocity field, while three tube pressure instrument data were measured with frequency of 50 Hz.
It has been observed that all the flow characteristics are spatially changed in transversal directions. Mean streamwise velocity and turbulent intensity profiles are diverted from available theoretical equations as secondary currents’ result. These diversions are clearer near side walls region. Also, shear stress in transversal direction is changed significantly. The undulation amplitude in transversal direction is 35% of shear stress mean value in span-wise direction.

Abstract Rivers provide water and energy for humans and the nature and it could be stated that providing water is the most crucial economic role of rivers. Water is deviated from its main course through the intakes in order to fulfill various purposes such as for agriculture, urban water supply, electricity generation and etc. Constructing the water intakes is one of the ancient cheapest methods to use the river water for different purposes. In the past, the gravity was used to collect the water from the rivers but it has now turned into an evolved hydraulic structure with designing criteria. Considering the fact that the river flow includes fine- and coarse-grained sediments and that the river regime changes during the floods, the intake’s inlet mouth must carry out the two essential duties: absorbing and controlling the flow deviated from the river and directing it into the intake channel and preventing the sediments and floating objects from entering the intake. Therefore, one of the crucial points to be considered in designing an intake located within a river is to select the conditions under which the water deviated by the intake will have maximum flow discharge and minimum sediment discharge. Using the new method, known as the soft computing, has gained significant popularity within the past decade due to the complexity of most engineering problems. One of the advantages of this method is its efficiency and desirable level of accuracy in solving complex and challenging engineering problems therefore, it brings accuracy and speed to the works of researchers. Numerous studies have been conducted to evaluate the flow in different types of open channels and hydrologic and hydraulic phenomena using the soft computing. The obtained results indicate the high accuracy of this method in solving complex water and hydraulic structures despite the few registered researches done on dividing open channel flow modeling. The present research examines the effect of the channel roughness on flow hydraulics and predicts the velocity in the intakes using a combination of artificial neural network and numerical model.
The artificial neural network is an idea based on the human mind, which is widely used in solving complex problems in different sciences. An artificial neural network generally comprises a number of connected nodes (known as neurons) including an input layer, a number of hidden layers and an output layer, each layer is made up of a number of neurons. Considering that the number of the hidden layers neurons is excessively great, the network will take an unacceptably long time to train for each value. An ANN model is presented in this study in order to predict the flow mean velocity. It is essential to model and verify a numerical model in order to train the model under flow conditions where there are no available experimental data. Ramamurthy et al.’s (2007) experimental model has been used in this study in order to verify the numerical model. The experiments have been conducted within rectangular channels. The main channel is straight while the branch channel is attached to the main channel with an angle of 90 degree. Therefore, Ramamurthy et al.’s (2007) experimental model has been simulated using the ANSYS-CFX software and verified through using the existing experimental data. After assuring the simulation accuracy in the CFX, different models have been conducted using the CFX and are used in training and verifying the ANN in order to predict the flow mean velocity.
The verification results, using a MAPE by 5 percent average error, indicates the high accuracy of the generated numerical model. After verifying the CFX model’s results and assuring that they were highly accurate, measures were taken to design five artificial neural network models with five different roughnesses by using the numerical and experimental data. The longitudinal velocities were predicted using the ANN model in cross sections, which possessed no experimental data, and then they were compared with the CFX model’s results. The result of this comparison indicates that the ANN model is highly accurate to predict the flow velocity in different areas of the intake channel moreover as the channel wall roughness increases from 0.0 to 0.0005 m, the flow longitudinal velocity drops significantly in most areas of the branch channel however as the roughness increases from 0.0005 to 0.001 m and more, the longitudinal velocities slightly drop. As the channel wall becomes rougher, the size of the flow separation zone decreases and the curve of the streamlines and the flow turbulence also decrease at the entrance of the branch channel

Abstract Numerous articles printed in recent scientific journals about the heavy metals contamination of drinking water indicate its universal importance. These metals are commonly toxic at very low exposure levels and have acute and chronic effects on human health. Heavy metals are a multi-organ system toxicant that can cause neurological, cardiovascular, renal, gastrointestinal, hematological and reproductive effects. The type and severity of effects depend on the level, duration and timing of exposure. Heavy metals are released by various natural and anthropogenic sources to the aquatic and terrestrial environments and the atmosphere and there are fluxes between these compartments. One of the main sources of heavy metals in drinking water comes from lead service pipes and the lead pipes inside dwellings. In Iran, lead in petrol is still an important source of exposure. Other sources include lead in paint, low temperature-fired ceramics, informal sector recycling of cars batteries, mine tailings and the air, soil and dust in the vicinity of point sources (e.g., smelters). Recent studies in Iran show that the presence of lead in drinking water is mostly due to pipes, fittings, brass or bronze water service connection valves, faucets, fixtures, and other end-use devices.
In this research, the heavy metal contamination of drinking water in Zanjan City from the water distribution system is studied. Two district within the city; (I) an older district with lead alloyed service pipes, and (II) a newer district with plastic water mains (polypropylene) were selected. Random periodic spot samples were taken manually to investigate the pollution incidents. The samples were collected in 1000 ml polyethylene bottles. The polyethylene containers were washed with dilute detergent and distilled water, then rinsed thoroughly with tap water and at last washed with an aqueous 10% nitric acid solution, drained and immediately caped. A few drops of concentrated ultra-pure HNO3 were added to the samples to reach pH < 2 in order to prevent the loss of metals and bacterial and fungal growth. To ensure the removal of organic impurities from the samples and thus preventing interference in analysis, the samples were preserved and digested with concentrated nitric acid. A total number of 200 water samples were taken using three different sampling methods, namely; 1) Fully flushed sampling: The Fully flushed sample is a sample taken after prolonged flushing of the tap in a premise in such way that water stagnation in the domestic distribution system does not influence the concentration of lead. In practice, a sample is taken after flushing at least three plumbing volumes. 2) First draw sampling: This sample is taken first in the morning before the tap in the premise has been used for other purposes. During the over-night stagnation period no water should be drawn from any outlet within the property. 3) Random daytime sampling: This is a sample taken at a random time of a working day directly from the tap in a property without previous flushing. Physical properties of the water samples, notably; Temperature (T), pH, Dissolved Oxygen (DO) and Electrical Conductivity (EC) were immediately measured at sampling stations using a portable digital pH meter (HACH HQ 40D). The samples were analyzed for Cu, Cd, Zn and Pb using an anodic stripping voltammetry method. Voltammetry is an electrochemistry method based on the study of current vs. potential relationships. This method play an important role in analytical chemistry with a wide range of applications, especially metal analysis and their speciation.
The concentration of heavy metals in water samples, especially those from treatment plant (source water) and newer city neighborhoods with polypropylene service pipes are below the permissible limits set by WHO and ISIRI. In contrast, 75% of samples contaminated by cadmium and 60% of those contaminated with lead are belonged to the older districts of the city with lead alloyed service pipes. In the first draw sampling method, the concentrations of metal ions in water samples were much higher than their concentration in other sampling methods. This is more prominent in the older district of the city. This can be attributed to corrosion of old lead alloyed pipes due to sufficient stagnation of water in service pipes. The concentrations of metals are lowest using the fully flushed sampling method and highest in the first draw sampling. This further supports the fact that old lead alloyed service pipes are mainly responsible for the heavy metals contamination of water samples from the Zanjan City water distribution system.

Abstract Although nature has the ability to deal with change, it cannot tolerate the growth of industries, deforestation and degradation of the environment. These huge and abrupt changes have caused to increasing the destruction of nature in recent decades, and increasing greenhouse gases. Ground water plays an important role in sustaining ecosystems and enabling human adaptation to climate variability and climate change. Groundwater resources are the largest store of fresh water in arid and semi-arid regions. In the areas where surface water resources are limited and inaccessible for people, groundwater can be considered as a secure resource. Climate change caused fluctuations in the ground water. Many wells dried up and some of them have lost their advantage due to the lack of available water. Climate change through changing climatic variables (including temperature, precipitation and evapotranspiration) directly affects surface water resources in many parts of the country. Besides, there have been many related problems such as drying up wells, reducing river flow, decreasing water quality, subsiding in lands, diminishing fresh water supplies and increasing salts in water. Climate change and its associated problems appear to be a serious challenge in the regions as Khorasan Razavi that 32 of 34 desert plains were declared prohibited. Due to cold and dry weather conditions and use of aquifers and wells as the main sources of water, Mashhad relies on groundwater as well as underground resources. The water resources of this plain are affected and threatened by changes in groundwater levels, temperature, rainfall, and frequent droughts. This research aims to study the groundwater level decline in Mashhad plain which is located in Khorasan Razavi province, northeastern of Iran.
The study tries to conduct a comprehensive study through the analysis of monthly precipitations data acquired from 34 synoptic, climatology and rain-gauge stations, monthly discharge of 13 hydrometric stations, and 60 groundwater piezometric wells. It confirmed the normality of climatic data, using the Kolmogorov-Smirnov test. The research also used multivariable regression methods as well as HadCM3 climate model scenarios to model groundwater perspective of Mashhad’s plains and to predict future climate variables, respectively. To compare the output scale of the mentioned model with the required scale of climate change studies, the data of temperature and precipitation were downscaled for the two periods of 2015-2030 and 2046-2065, under three scenarios of A1B, A2 and B1 using the LARS-WG5.5 model. It later employs geographical weighted regression (GWR) to model the ground water level (as the dependent variable) with climatic parameters of temperature, precipitation, and evapotranspiration (as independent variables).
Mashhad’s prospect of precipitation and temperature revealed a rainfall reduction for the cold season, its increase in the warm season, and at least one-degree increase compared to the base year. Modelling of groundwater level changes (using the parameters of rainfall, temperature and evapotranspiration) showed decline in groundwater levels in the range of at least 0.2 meters and maximum 0.7 meters. The research provides an intelligent simulation for fluctuations of groundwater using multiple regression models and the historical data of rainfall, temperature and evapotranspiration, which helps to estimate underground water level in the coming years. The results indicate a drop in the water level of all studied piezometric wells, under three climate change scenarios for future periods. The study concluded that the most important reason of water loss in Mashhad’s plains is the human overuse of groundwater. Fluctuations in groundwater assessment have shown that the highest annual fluctuations of groundwater were occurred in the southern part of Mashhad plain. Fluctuation assessments of surface water showed negative fluctuation in upstream and positive in downstream. These issues reflect the role of human factors in increasing the groundwater level in downstream and reducing the level in upstream. Modeling of groundwater level fluctuations with climate parameters (temperature, precipitation and evapotranspiration), using GWR and OLS models, represents superior of geographical weighted regression model compared with ordinary least squares models. Fitting weighting matrices to GWR model showed high accuracy of Gauss method than the other studied methods. The important issue that was obtained from simulations of Mashhad station is reducing the variance of rainfall in A1B emission scenario, indicating the absence of stable conditions in the future. The results of this research showed that the most important reason for the drop in Mashhad plain is overuse of groundwater.

Abstract Groundwater is the most important water resource in Iran that provides the majority of agricultural and urban demands. In recent years, natural recharge and extending urban areas caused the water table in alluvial Bojnourd aquifer to be raised. Transferring water from Karstic aquifers and Shirin Dareh dam intensified this problem, especially in the fine grain areas of the city. Supplying water from alluvial aquifer in the natural and urban areas, low thickness and discharge potential of alluvial, as well as development of Bojnourd were caused by the enhancement in the absolute height of water table in the alluvial aquifer. Also, in the plains such as Bojnourd that urban uses are dominant, according to the mentioned problems, water supply is very important. Therefore, it is essential that the current situation and future of Bojnourd alluvial aquifer to be identified and the solutions be managed to eliminate probable problem. Numerical models of groundwater flow can be used as the tools to test the effect of management decisions, but usually lack or incomplete information of the hydraulic characteristics of the aquifer causes limitation in use of these models. Nowadays, in the all of the world many studies are ongoing about of stratigraphy of aquifers in order to more understanding about the complicated conditions in the water flow hydraulics. So, it seems that understand of Bojnourd plain aquifer stratigraphy and a better estimation of the hydrodynamic coefficients can help to make decisions appropriately, to deal with the problems. The aim of this research was to make a model for Bojnourd aquifer with emphasis on hydro-stratigraphy.
According to the variety of Bojnourd aquifer sediments, it cannot be assume as a done-layer aquifer. So, in order to reduce uncertainties, as well as developing and enhancing a conceptual model, natural features that could impact groundwater system (especially stratigraphy of sediments) has been tried to identify and introduced to models. The effective factors include: geological studies, geophysical sections, using of observational wells and determination of the recharge and discharge. In this study, to verify and judgement models with fifteen different lithology cross sections in aquifer were used. Rockworks software was applied to obtain the appropriate layer of the aquifer that eventually lead to more accurate estimation in three-dimensional lithology model. Rockworks software uses lateral Bending Horizontal method to interpolate lithology of wells log data. Then, using three-dimensional model techniques in Rockworks16 software, the three-dimensional model of the aquifer lithology with all available data and information, i.e., logs and geophysical studies was obtained. Three-dimensional models of geology are as subsurface three-dimensional representative that show spatial relations of logs lithology and lenses. Interpolating between the existing logs can fill the undefined gaps between them and increasing the amount of boreholes in aquifer adds the accuracy of these models. The results of three-dimensional models represent three-dimensional groundwater flow model of the aquifer system. The result of lithology modeling of aquifer was composed of four soil textures including of coarse grain, medium-grain, fine grain and very fine grain with four layers and with the thickness of 30m that was important to version1.7.10 of GMS software.
The model was run in steady state for October 2000. In the first step, the initial model coefficients were calculated. After running the model in steady state, the mean square error was 2.77 m. In the next step, the results were better with changes in the soil hydraulic conductivity values and the mean square error was 0.794m after calibration. Heterogeneity and lenses in the aquifer system caused change in hydraulic conductivities of coarse to very fine-grained sediment, so the identification of aggregation and different genders, lithology of the aquifer with higher accuracy was achieved. Consequently, the hydrodynamic coefficients (k,s) could be estimated more precisely. So, considering that the aquifer materials are heterogeneity, the hydraulic conductivity values were obtained as 8.1, 6.7, 1.9 and 0.4 for the soil textures of coarse grain, medium grain, fine grain and very fine grain, respectively. Totally, changes of water level were between 1020 to 1080 meter and in the first layer while the northern and eastern parts of aquifer were dry. According to flow, budget of the aquifer in multi-layer model was obtained with acceptable accuracy, comparing with one-layer models. The calculated flow budget by the model shows that the aquifer layer was in balance with the amount of input and output, approximately.

Abstract Introduction:
Water is a valuable asset for agriculture in arid and semi arid regions, worldwide. Reducing water leaks from the irrigation canals will save more water and leads to economic agriculture. Previous studies showed the importance of seepage assessmemt in irrigation canals. Assessment of seepage can be done by practical, theoritical and empirical methods. The review of literature reveals that the direct or practical methods can be more trustable comparing to theoretical or empirical methods or models. Ponding and inflow-outflow methods were widely used as direct or practical methods for seepage evaluation in irrigation canals. Use of empirical seepage formulas needs less cost and time comparing to other type of methods. However, the empirical models have different estimation accuracy and needs to be evaluated more. It is recommended in literature that the empirical models should be calibrated for a specific region before use. Simple empirical models have an estimation error about 15 percent due to direct measured values.
Methods:
In present study, seepage was measured and compared in three irrigation earth canals in Darab plain using inflow-outflow method and various empirical formulas. These three canals named Hasanabad Canal, Mansuriyeh Canal, and Janatshahr Canal. The soil texture class of these three canals is Loam, Clay Loam and Sandy Loam, respectively. The canal flow velocity was measured using Valeport flow meter in the beginning and the end of three distances of 200 meters along each canal. The discharges were computed by multiplying the mean velocities and flow areas. Difference between the inflow and outflow discharge shows the canal seepage in the selected reaches. The Ingham, Davis-Wilson, Molesworth-Yennidumia, Affengendon, Moritz, Misra, Garg, Indian Punjab, Egyptian Irrigation Department empirical models were used for the study. Mean absolute error, root mean square error, normalized root mean square error, coefficient of variation of root mean square error, and ?2 test were used for the comparison of estimated and measured values. These empirical formulas were calibrated and validated due to the inflow-outflow method.
Results:
Results showed that the Moritz and Affengendon formulas with mean absolute error of 49% and 1445% percent had the least and most difference with inflow-outflow method before calibration. The error of estimation of the other formulas was about 125%. The highest estimated seepage was in the Affengendon formula, while the lowest was in the Ingham and Indian Punjab formulas. Comparison of estimated seepage values using t-test shows that the difference between the empirical seepage formulas is significant at 95% confidence probability. However, the difference between Moritz and inflow-outflow methods, Ingham and Molesworth-Yennidumia, Ingham and Indian Punjab, Molesworth-Yennidumia and Indian Punjab formula, Garg and Davis-Wilson formula was not significant at 95% confidence probability. The seepage estimation error of uncalibrated Ingham formula was about 95%, while for calibrated formula was less than 11 percent. The error of seepage estimation using uncalibrated Moritz and Molesworth-Yennidumia formulas were about 52 and 96 percent. This error for the uncalibrated Indian Punjab, Affengendon, Egyptian irrigation department, Garg and Misra formulas were about 95, 1220, 90, 92 and 68 percent, respectively. Results also showed that the error of calibrated Ingham, Molesworth-Yenidumia, Moritz, Davis-Wilson and Affengendon models, was about 7, 8, 9, 10, 10 percent comparing to inflow-outflow method, respectively. After these five formulas, the error of estimation of Garg, Egyptian, Misra, and Indian formulas were 17, 18, 20 and 20 percent, respectively. In order to validate the evaluated empirical formulas, some statistical parameters such as root mean square error, normalized root mean square error, coefficient of variation of root mean square error, and ?2 test were used. Results shows that the evaluated empirical formulas can be sorted from the better validated to the worse validated as Ingham, Molesworth-Yennidumia, Davis-Wilson, Moritz, Affengendon, Garg, Egyptian Irrigation Department, Misra and Indian Punjab. The ?2 values of the evaluated empirical formulas were 0.077 for Ingham formula to 0.757 for Misra formula. It can be concluded from this research that the uncalibrated empirical seepage formulas had significant difference to the inflow-outflow direct method. However, all of the calibrated formulas had a mean relative error less than 20 percent comparing to inflow-outflow method. Ingham formula was the best formula due to less calibration error. Moritz and Misra formulas had the best and worst validation condition in the study, respectively.

Abstract Levees are man-made embankments built to prevent rivers from overflowing their banks. A levee is a naturally elongated ridge or artificially constructed fill or wall that regulates the water level. It is usually earthen and often parallel to the course of a river in its floodplain or along low-lying coastlines. The levee construction is a common and very old method of river flood control recently used considerably as an engineering operation to reduce or prevent the detrimental effects of floodwaters. It can be used either alone or together with other methods to minimize the floodwater damage. Engineered earthen levees are of three general types: compact, semi-compact, and uncompact; the former are usually and traditionally used in areas of high property values, high populations, high land use, or in controlled compaction, steep-sloped embankments utilized on good foundation conditions during construction. The semi-compact or uncompact levees are generally used in low value, poor foundation areas or those with high rainfall during the construction season. Compared to other floodwater control methods, levees are more efficient because they are not only quite cost-effective, but also provide more factor of safety for slope stability. Artificial levees are aimed at preventing the adjoining countryside flooding and slowing the waterways' natural course changes to provide reliable shipping lanes for maritime commerce over time; they also confine the river flow causing higher and faster water flow.
Levee construction materials should be coarse enough to withstand the erosion caused by the flowing water, their shear strength should be enough to satisfy the levee's slope stability, and they should be adequately impermeable meaning that they should also contain fine aggregates to prevent the extra seepage that has undesirable effects on the levee's slope stability; therefore, making specific arrangements to reduce repercussions deems necessary. Massive constructions that require large amounts of materials need to use the available on-site materials to reduce the transportation distance and hence the project construction cost; using on-site materials is a significant advantage the levee construction enjoys. As mentioned before, since the levee construction needs both coarse- and fine-grained materials to reduce permeability, the best choice can be the coarse-grained soil containing clay; therefore, both GC (clayey gravel) and SC (clayey sand) soil types take priority over any other types. Hence, evaluating the amount of the soil fine aggregates and the effects of compaction percentage on the permeability coefficient and on other strength parameters to meet the economic, speed, and time requirements of the levee construction is quite important. This research studies the effects of compaction percentage and the amount of fine aggregates on the SC soil permeability and on the steady and unsteady seepage flow through levees. Accordingly, three levee samples A, B, and C (from Mehran River borrow area) with respectively 12.8, 20, and 28.4% fine aggregates and 60, 70, 85, and 100% compaction have been selected to carry out the permeability tests.
Results of tests with different compaction and fine aggregate percentages showed that an increase in the percent compaction of each sample (from 60 to 100, 70 to 100, and 85 to 100) decreased the permeability coefficient 25, 14.3, and 8.91 times, respectively. At every compaction percentage, sample A's permeability coefficient was 1.2 times that of sample B and 1.69 times that of sample C and that of sample B was 1.41 times that of sample C. Next, using the numerical modeling, both the flow rate (in the steady state) and phreatic line (in the unsteady state) through the levee were studied with different compaction percentages and the results showed that in simulating the unsteady seepage through the levee the phreatic line did not intersect the downstream slope and was significantly far from it. The results of this research can be used to either design or construction of the levee; furthermore, it can used to analyze the effect of the soil compaction percent on permeability parameter during construction of levees.

Abstract One of the important parameters in agriculture, regarding to assessing irrigation systems, is water distribution uniformity coefficient (CU) in sprinkler irrigation. The first study of sprinkler irrigation uniformity was executed by Christiansen (1942) in California that led to introduce the Christiansen uniformity coefficient. Nowadays, it is very common to use Christiansen uniformity coefficient in sprinkler irrigation systems. Many researchers have investigated water distribution uniformity coefficient in solid set sprinkler systems. While, other researchers such as Hart and Reynolds (1965), Karmeli (1997), Vories and Bernuth (1986), Dabbous (1962), Heerman (1983), Keller and Bliesner (1990), Carrion et al. (2001), Montero et al. (2003) and Bavi et al. (2006) have investigated different aspects of water distribution uniformity coefficient. A sprinkler water distribution pattern depends on the system design parameters such as: the sprinkler spacing, operating pressure, nozzle diameter, as well as environmental variables such as: wind speed and direction. The sprinkler irrigation distribution patterns have been characterized by various statistical uniformity coefficients. Also, various coefficients of uniformity (CUs) have been developed over the past decades. CU amount of water sprinkler operating depends on different pressure heads (P), riser height (RH), distance between sprinklers on lateral pipes (Sl) and the distance between lateral pipes (Sm). The best combination of the above parameters for maximum CU is still unknown for applicators. Many researches, such as Hezar Jaribi et al. (2009), have been done to estimate various relationships using different algorithms. Different researchers have used various concepts to express the coefficients of uniformity; hence the equations lead to different results in the expression of the distributed water uniformity in the same fields.
This paper evaluates different uniformity coefficients, using Bacterial Foraging Algorithm (BFO), to propose the best and optimized equation for CU. Generally, the task is to optimize certain properties of a system by pertinently choosing the system parameters. So, in this study, CU has been estimated by Bacterial Foraging Algorithm, and an equation was proposed with the optimized coefficients for CU. The field experiments were conducted on a farmland located in Hashem Abad Agricultural Research Station of Gorgan Cotton Research Institute, about 11 kilometers northwest from Gorgan, Iran. In this area, the lands were irrigated by solid set sprinkler irrigation systems. The sprinkler uniformity tests were conducted using rain-gauge for measuring uniformity coefficients. CU quantities of zb model sprinkler (made in Iran) were considered with three different pressure heads (2.5, 3 and 3.5 atm), two riser heads (60 and 100 cm) and seven sprinkler arrangements (Sl×Sm including: 9×12, 9×15, 12×12, 15×12, 12×18, 15×15, 15×18m). In this study nonlinear equation uniformity coefficients in sprinkler irrigation have been optimized by using Bacterial Foraging Algorithm (BFO). Typically, the BFO consists of four main mechanisms including chemotaxis, swarming, reproduction, and elimination-dispersal event. Totally, the algorithm was run more than 70 times for various conditions and obtained the best case. While optimizing CU Equation by Bacterial Foraging Algorithm (BFO), The best results obtained in S, Nc, Nre, Ned, and C(i) which were equal to 24, 500, 8, 8 and 0.01, respectively. The outcome of this optimization is the following equation which was derived to estimate the Christiansen uniformity coefficient (based on the specified working pressure of the sprinkler, sprinkler height, distance between sprinklers on the pipes side and distance between side pipes).
To evaluate the proposed optimal equation, it was used to estimate Christiansen uniformity coefficient distribution of the 70% of the experimental data. Then, the model obtained from 70% of the data was verified with remaining 30% of the experimental data. The estimated Christiansen uniformity coefficient distribution (obtained from the equation) revealed high accuracy, compared with the 30% and 70% of the observed data.
Result showed that the maximum absolute error between the outcomes of this algorithm with the measured values was less than 3%. This error was based on using 30% of the data. Also, the root-mean square error (RMSE) was equal to 2.13. Therefore, it is revealed that this algorithm has high accuracy in estimating water distribution uniformity coefficient. Generally, it can be said that Bacterial Foraging Algorithm is more acceptable for optimizing nonlinear functions, comparing with other algorithms such as genetic and differential evolution algorithm. Also, it has much higher rate of convergence, whereas does not make local optimal problems.

Abstract Deficit irrigation is the strategy used to produce a crop with maximum income and profits. This method has attracted attentions due to the intensification of the water crisis and population growth. Basinger and Hellman (2006) suggested that deficit irrigation increases the water use efficiency by 72%, but it has little effect on reducing the amount of the product. Negaz et al. (2013) experimented the efficiency of optimum water use of lettuce, in different irrigation regimes (30, 60 and 100% of plant water requirement), in Tunisia. The results showed that the highest water use efficiency was related to 30% water requirement and the lowest was 100% water requirement with 34.3 and 14 kg/m3, respectively. Haghighi (2008) compared the PRD (Partial root zone drying) irrigation method and conventional irrigation on greenhouse tomato growth and concluded that PRD treatment increased the water use efficiency of the plant and increased the total soluble solids. While, no significant difference was observed between the two treatments in the number of fruit, color and fresh and dry weight of root. On the contrary, PRD reduced the dry weight of the shoot and the weight of the fruit. Also, the rate of handling and distribution of red fruit was higher in PRD treatment.
This study were investigated the effect of regulated deficit irrigation (RDI) and PRD on tomato, under hydroponic culture conditions. The treatments of experiment consisted of five treatments: RDI irrigation at 85 and 70% of plant water requirement and PRD irrigation at 85 and 70% of the plant water requirement, and control treatment. The experiments were carried out in a completely randomized design with four replications. The water requirement of the plant was determined by the evaporation rate from class A evaporation pan (located in the greenhouse) and multiplying it at the plant shadow level. To feed the plants, Resh nutrient solution (2005), which contains macro and micro nutrients for plant growth, was used. For preparing of solution, urban drinking water was used with EC=1.8 mS/cm. The leaf area was measured every two weeks by a ruler. After applying the treatments, the greenhouse tomato product was manually harvested in 5 times. The number of harvested fruits only consisted of fruits that were fully grown and ready to be harvested. According, every 2 weeks, the fruits were counted, harvested and weighted. After the end of the growth period, the fresh and dry weight of root, fresh and dry weight of leaf, leaf water content, leaf area, fresh and dry weight of stem and biomass and dry weight of plant were measured. Also, leaf area index (LAI), special leaf area (SLA), leaf area ratio (LAR), harvest index, water use efficiency and efficiency of biomass water use were calculated.
The results showed that different methods and levels of deficit irrigation had significant effects on fresh and dry weight of root, fresh and dry weight of stem, plant dry weight, fruit weight and water use efficiency. But, the levels of applied water did not significantly affect fresh and dry weight of leaf, leaf water content, leaf area, leaf area index, special leaf area, leaf area ratio, biomass weight and harvest index. The results showed that the plant with irrigation application of 85% of plant water requirement showed different results in fruit weight index and water use efficiency, in comparison with the control treatment. Deficit irrigation of PRD treatment in the weight of fruit increased by 3.5% and water use efficiency increased to 22 percent, compared with control treatment (2572.5 g and 16.07 kg/m3, respectively). But, RDI treatment in fruit weight decreases by 20% and reduces water use efficiency by 5.5% compared with control treatment (1997.8 g and 12.48 kg/m3, respectively).With reducing applied water to 70% of plant water requirement, the behavior of the plant was different, and RDI treatment showed a lower reduction for the fruit weight index and water use efficiency than PRD treatment. Accordingly, the RDI treatment in fruit weight decreased by 35% and water use efficiency decreased by 7% (1614.2 g and 12.24 Kg/m3, respectively). While, PRD reduced 52% in fruit weight and decreased 31% of water use efficiency (1189.5 g and 9.02 Kg/m3, respectively). Eventually, PRD treatment with 85% of plant water requirement was selected as the best method for hydroponic culture of tomato in greenhouse.

Abstract In the recent decades, due to the complexity and nonlinearity of aquifers, artificial intelligence (AI) models have been extensively used in aquifer modeling. The purpose of this research is GWL predicting using hybrid of Self Organizing Map (SOM)-clustering method with Artificial Intelligence (AI) approaches, including support vector machine (SVM) and fuzzy logic (FL). The basic concept and theory of SVM was introduced by Vapnik (1995). The SVM implement the structural risk minimization (SRM) principle. The most important concept of SVM is minimizing an upper bound to the generalization error, instead of minimizing the training error. SVM has two outstanding of excellent generalization capability, and sparse representation. Zadeh (1965) introduced the fuzzy sets. A fuzzy system includes three parts: 1. Fuzzification, the degree of membership in a fuzzy set is defined through a membership function; 2. Fuzzy rule, A fuzzy rule-based model operates on an if-then principle; 3. Defuzzification. Basic FL models and clustering techniques have been combined to provide objective FL modelling techniques, but there are variations with respect to the type of their output membership function and the implication methods. As an efficient mathematical tool, SOM may be used to visualize a high-dimensional data set (Nourani et al, 2016). SOMs reduce data dimensions and show similar patterns. Each SOM network typically includes one input and Kohonen layer. This method may reduce the aquifer's heterogeneity due to unsupervised classification of the aquifers. Based on availability of data, 10 observation wells (OW1-OW10) in the study area were selected for predicting groundwater level. The monthly groundwater level at previous time (GWL_(t_0-1)), Monthly temperature at current time (T_(t_0 )), Monthly precipitation at current time (P_(t_0 )) and monthly discharge of the Zola river at current time (Q_(t_0 )) were used as inputs of models. All data were monthly, of 15 years (2001-2016). 80% of data were used for training and 20% for test step. In order to examine the effectiveness of the models in predicting GWL, the performance measure was quantified for all models using three indices: Root Mean Squared Error (RMSE), Coefficient of determination (r2) and Nash-Sutcliffe Efficiency (NSE).
The Salmas plain with an area about 550 km2, located at north of West Azarbaijan province, northwest of Iran. This area is a part of the Urmia Lake catchment and considered as a semi-arid and cold zone, with average annual temperature of 10.36 °C. Of the 27 observation wells (OW) in the aquifer of Salmas plain, 10 of them were selected to predict the monthly groundwater level. Due to hydrogeological and morphological heterogeneous nature of this aquifer, the SOM-clustering method was used to classify the observation wells. This method produces three groups, labelled as G1, G2 and G3. Sugeno Fuzzy Logic (SFL) models were implemented for each of the three groups of observation wells, using the Subtractive Clustering (SC) technique by systematically increasing the cluster radius from 0 to 1. The input and output clusters were created using the Gaussian and linear membership function, respectively. Least Squares-SVM (LSSVM) type was applied to predict GWL. Selecting suitable kernel function and optimized value of kernel (?) and regularization (C) parameters is important step in implementing SVM. The optimized value of ? and C were determined based on minimizing RMSE. The SFL and LSSVM models were built in three groups for predicting GWL at OW1-OW10 of the study area using training data. The three performance measures of RMSE, r2 and NSE for each of two models (SOM-SFL and SOM-LSSVM) at each of observation wells were calculated. The performance of SOM-SFL and SOM-LSSVM models during the testing was evaluated using the three performance measures for training the models and compared with the results obtained.
This research investigated the hybrids of SOM-clustering method with SFL and LSSVM approaches for predicting groundwater level. Performance measures of these models indicate that their results of two hybrid models (SOM-SFL and SOM-LSSVM) are acceptable. In group one (G1) of observation wells (OW1 and OW7), SOM-LSSVM performs better than SOM-SFL. In OW2, OW6 and OW9, obtained results show that SOM-SFL model has better performance. The proposed hybrid models in this research (SOM-SFL and SOM-LSSVM) could successfully be used in predicting GWL. Combine the results of two models and using of multiple models can improve the final results.

Abstract The Jiroft Plain Basin is part of the Jazmurian Waters Basin, located in the south of Iran, Kerman province. The uncontrolled extraction of groundwater from the aquifer of the forbidden Jiroft plain has caused the aquifer's water level to fall, which could seriously threaten the agricultural economy of the region. If this action is not considered seriously, this plain will not only exacerbate environmental impacts in the future, but will also face economic and social problems. The purpose of this paper is to identify the status of Jiroft Plain Aquifer in recent decade and compared the cost of water extracting from wells in two types of water extraction technology: diesel and electric pumps.
Initially, based on available statistics and information, which collected from Iran Water Resources Management Company, Kerman Regional Water Company and Jiroft District Water Company, the status of the groundwater Aquifer in Jiroft plain has been investigated. Then the cost of water pumping from wells with electric and diesel water removal technology was compared. To achieving the study purposes, questionnaires was collected from beneficiaries of Jiroft plain agricultural water wells in the crop year 2014-2015.The sample size was determined by the simple random sampling method. In the meanwhile, the data of the questionnaire include: crops production cost in 2015-2016, how to use water wells, energy consumption, and cost of energy and pump maintenance costs. To sum, 227 questionnaires were collected that 202 cases of them used electro pump technology, and 25 cases used diesel pumps for withdrawing water from wells.
The results showed that average depth of electric and diesel wells were 101 and 55 meters, and their average discharge was 25 and 15 liters per second, respectively. It can be seen that the electric pump, in comparison with the diesel pump, results in more drainage and further increase in annual drop of groundwater level. Whereas, its energy cost is less than diesel pump. Also, the results showed that the cost of water extraction per cubic meter of water with electro pumps and diesel pumps are 169 and 365 IRR, respectively. It means that extraction cost with electro pump is about half of diesel pump cost. So, if we change the technology of water extraction from diesel to electro pumps, we can save 1.525.670 and 3815920 IRR on cultivating cost for one hectare of wheat and orange, respectively. The wells with electro pump technology, in comparison with wells with diesel engine motors, have more average depth and average discharge rates. From working hours' side, electric pump is more than diesel pumps. Therefore, by using electric pumps, more water will extracted from groundwater resource and eventually decrease the level of water aquifer. Although the converting pump type policy from a diesel to electric pump has been supported by the government in recent years and has been included subsidized facilities, it has caused negative effects. This policy could save up to 50 percent of pumping and pump maintenance costs for agricultural operators and consequently reduced the cost of production but the lack of some policies by the government such as pricing, tariff and incentive policies to control the volume of groundwater extraction has led to increase a pressure on groundwater resources. Farmers who have economic logic accepts the fixed costs of changing diesel pump to electric pump to reduce production costs in the long run and exploit the benefits of more water extraction, but the policy makers have not taken any action for maintaing the groundwater resources of the plain. Therefore, the fallowing approaches are suggested: implementing policies to control the volume of water extraction to prevent the continuation of the process of discharging strategic reserves, contributing to the equilibrium of the aquifer's plain water level, reducing the discharge rate of the exploitation at the request for change of diesel pump to electric pump

Abstract Introduction Considering the vital importance of water in arid and semi-arid regions like Iran, conservation and optimal use of water resources is necessary. In this regard, increasing conveyance efficiency and reducing water losses in distribution canals are very imperative. Low water conveyance efficiency in distribution canals is mainly due to seepage losses in channels. However, since infiltration and seepage cause groundwater recharge, it is sometimes beneficial. Reviewing the literature revealed that some specialists believe lining channels is not justified, technically and economically. Other experts do not reject lining at all, however, suggested that since seepage could help groundwater recharge indirectly, in regions which there is no ponding problem, channel lining should justify from the economic point of view. Additionally, another group of researchers found that although construction costs of lining seems very high, considering its long term benefits for countries with vital need to water in future, such as Pakistan and Iran, is economic. Meanwhile, according to some studies, concrete lining is not economically justified. Based on numerous different and sometimes opposite opinions regarding economic justification of lining, it seems necessary to investigate this issue on regional scale. Thus, the current study aimed at economic analysis of infiltrating water from unlined canal to groundwater and pumping again through wells to surface, in comparison with lining canals and not allowing to seep. Method In order to do this research, the concrete canal of modern Irrigation and Drainage network of Gandoman and Boldaji, Borujen city, Chaharmahal and Bakhtiari province, with ۱.۳ m width, ۱.۸ m depth and ۶.۵ m top width, was chosen as prototype. In order to analyze the lining, this channel was compared with an earth canal, having the same dimensions. Soil texture was determined using hydrometer method, which was obtained as loam that was constant to the depth of water table (۶.۷۹ m from soil surface). In order to estimate the amount of seepage in the earth channel, using physical modelling and dimensional similitude relations and considering ۰.۱۳ as scale ratio, dimensions and discharges of lined canal have converted to laboratory dimensions at soil mechanics lab of Shahrekord University. Lining lifetime was selected۱۰, ۲۰ and ۴۰ years, and the interest rates were ۱۲, ۱۵ and ۱۸ percent. Results Based on the results, the measured seepage loss in experimental flume of laboratory for the unlined and lined canal was ۲۶ and ۱۱ %, respectively. According to calculations, the price of groundwater in the study region is nearly ۰.۲۴ cents per cubic meter. Bearing in mind the low depth of groundwater in the study area (۶.۷۹ m), this small value in comparison with the price of surface water (۰.۳۱ cents per cubic meter), will justify. According to ‘base unit price index for irrigation and drainage works’, the costs of earth and lined canal construction with length ۳۰۰۰۰, top width ۶.۵ and bottom width ۱.۳ m, was calculated and obtained as ۱۰۷۶۸ and ۹۱۰۶۰ M.Rials respectively. It has been noticeable that for construction of both type of canals, half of cutting practices have considered in stony lands and the remaining in earth lands. Furthermore, renovation and maintenance costs for unlined channel were taken into consideration, which have been applied from year ۱ to ۱۰, ۲۰, and ۴۰ years. These costs have increased by ۱۵% increase per year (according to the inflation rate). Results showed that increasing the interest rate from ۱۲ to ۱۸% has been resulted in decreasing both NPV and B/C values (except for B/C in concrete-lined canal, ۴۰ years). On the other hand, increasing the lifetime of lining from ۱۰ to ۴۰ (constant interest rate), the NPV and B/C values were increased at first and then were decreased. Investigating the calculations showed that after ۳۰ years, with maximizing the maintenance costs of lined canal, its costs exceed its benefits. Therefore, lining canal with the mentioned properties will not be economical after ۳۰ years. Consequently, with all lifetime values, the earth canal is more economic than the lined one, considering both economic indices and for all interest rates. Therefore, it could be concluded that when the water table depth is ۶/۷۹ m and it is possible to pumpage the infiltrated water from well (while the canal is unlined with a loam soil), which are the properties of Borujen region in the current study, lining with concrete is not justified economically.

Abstract In this study, water exchange in normal and severe drought conditions was also investigated. Based on the historical time series of zayanderood stream flow in Sadtanzimi, the water years ۱۳۷۳-۱۳۷۴ and ۱۳۷۹-۱۳۸۰ were selected as normal year and severe drought condition, respectively. By derived equations, outflows of three reaches were obtained under normal and drought condition. Based on the results, in normal condition net exchange of surface water was negative in three reaches, and only a small amount of ۵ million cubic meters per year has been added to surface water in the second period. The results in normal year showed that surface water was fed by groundwater in the first reach and in the other two reaches fed groundwater. Compared to the normal water year, significant changes were observed in the exchange of surface water with groundwater and atmosphere in severe drought conditions. In the first reach, surface water gain by groundwater was observed, which this increase is ۱۷% of outflow of this reach during drought conditions. During the drought, only the first period has not faced with shortage. The flows and water exchange in this situation have been such that the observed outflow of the three studied reaches is reduced by half the inflows. Surface water of the first reach has net gain in drought conditions. While under normal conditions, this interval was purely water withdrawal. Duo to the lack of accurate data on withdrawals and return flow, these components of the surface water balance were considered as annual average. However, the obtained results and their comparison with the data and information in the previous studies showed that the proposed method is a suitable toll for assessing the exchange of surface water with groundwater. Therefore, in future studies it is suggested studying this method with more accurate data on exploitation and return flow. Keywords: Surface water and Groundwater Interaction, Streamflow, Mass balance, River reac

Abstract In recent decades, the use of saline water in agricultural production has increased dramatically due to the reduction of fresh water resources. But, safe use of saline water requires proper irrigation management. This experiment was carried out to study the effects of water salinity on yield, water use efficiency and fruit quality of drip irrigated tomatoes in southern Iran (Bushehr) with arid and semi-arid weather during one cropping season (۲۰۱۰-۲۰۱۱). The experiment was designed as split plot in a randomized complete block design (RCBD) with four levels of water salinity (۱.۱, ۳.۷, ۵.۵ and ۷.۵ dS.m-۱) and three levels of irrigation intervals (۲, ۴ and ۷ days) with three replications. According to the results, with increasing irrigation interval from ۲ to ۷ days, the mean values of crop yield (Y), irrigation water use efficiency (IWUE) and fruit weight (FW) decreased by ۲۰, ۱۹ and ۲۶% respectively. Also, with increasing salinity of irrigation water from ۱.۱ dS.m-۱ to ۷.۵ dS.m-۱, these values decreased by ۳۳, ۳۹ and ۳۲% respectively. In general, under climatic conditions and soil characteristics of the experiment site, yield loss due to water salinity was far lower than that reported in FAO No. ۲۹ paper (Ayers and Westcott, ۱۹۸۵). Also, with increasing irrigation interval and salinity of water, fruit quality increased in terms of the amount of soluble solids (TSS).

Abstract Limited water resources will be available if the quality is desirable today, by entrance of extensive industrial activities and the use of fertilizers in agriculture, the most important source of human life is in dangerous. According to researchers result, groundwater contamination is often due to poisoning wastewater from industries or from wastewater reservoir resources, one of the most important pollutants is nitrate. Nitrate in nature can be exchange to nitrogen or other forms by microbial activity. There are various methods for removing nitrate from water those most commonly using denitrification substrates. It has been proposed to create a wall of denitrification as a buffer against nitrate contaminated streams as a suitable way to prevent the entering of nitrate into groundwater resources and then surface water resources. In this research, tried to study the effect of nitrification using denitrification substrates that containing a mixture of soil and four carbon sources of liquid including glucose, acetate, ethanol and methanol. In this research, a Plexiglas column was used as a pillar of Marriott and water source and a porous media column filled with soil with a loamy clay texture of ۵۰ cm length and ۱۰ cm in diameter. Potassium nitrate salt was used to make a concentration of ۱۰۰ mg / L nitrate solution. This study was carried out in two ratios of ۱.۵ and ۳.۵ C / N, and the concentration of nitrate was measured until when the pore volume reach to ۱۰ and also concentration of nitrate output was stabilized. This research was carried out at the research laboratory of the Water Engineering Department of Shahrekord University. After about ۲۵۰ hours from the start of the biological removal process, it was observed that the concentration of output nitrate was almost constant and there is not much change. This phenomenon may be due to the growth of bacteria because of the favorable growth conditions at the beginning of the experiment and the optimal separation of nitrate in a process and, finally, the lack of one of the factors affecting growth due to the maximum growth of bacteria. It is clear that at the end of the experiments and after the concentration of nitrate output from the column was fixed, green algae were observed in parts of the absorption column due to bacterial growth and massification. The removal efficiency of nitrate by glucose, acetate, ethanol and methanol was ۹۷.۸۳%, ۹۷%, ۹۸.۶۶% and ۹۹% respectively, and so methanol had the most efficiency in nitrate removal. Methanol, with ۹۹% removal efficiency, can easily remove nitrate to a concentration of ۱۰۰ mg / L at groundwater reduce to ۲.۱ mg per liter. Methanol with ۱۳۱,۰۰۰ bacteria had the highest bacterial growth rate in the C / N ratio of ۳.۵. In fact, by increasing the concentration of carbon, the growth rate of the bacteria increased and the concentration of nitrate decreased. In statistical analysis, both carbon-to-nitrogen ratios showed significant differences in carbon-nitrogen ratios other than glucose-acetate, with a significant difference in the mean carbon concentration. Also a paired test between different concentrations of a carbon source showed that there is a significant correlation between concentrations of ۱.۵ and ۳.۵ for each carbon source.

Abstract Abstract
Introduction: Soil organic matter plays an important role in improving physical, chemical, and biological properties of soil in agriculture. Biochar is a carbon-rich organic material that produced by pyrolysis of biomass under oxygen limited conditions and it improves the physical and chemical properties of soils. In recent years, biochar application in soil has been considered as a desirable way to improve physical conditions and increase soil moisture storage capacity. Achieving any of the above objectives depends on the physical and chemical structure of the biochar and its application to the soil.The main objective of this paper was to evaluate the effects of biochar, produced from date palm’s leaves, on the physical properties and hydrological behavior of a sandy clay loam soil by carrying out under greenhouse conditions.
Methods: For this aim, Pyrolysis at 400 degree of centigrade at 2 hour in an electric furnace biochars was obtained. Biochars were in powdered form and evenly added to soil (air-dried and passed through a 4 mm sieve) and incubated for 2 months. Therefor with determination of soil moisture content at field capacity, one, three, six and nine months after mixture soil and biochar, were measured hydraulic conductivity (kS) by taking soil samples from the pots. By measuring gravimetric water content at saturation percentage (SP), field capacity (FC) and permanent wilting point (PWP), plant available water content (PAWC) and relative field capacity (RFC) calculated. The Factorial experiment was conducted in a completely randomized design with two factors. The factors of this experiment was including amendment (palm’s leaves and biochar), application level (0, 0.5, 1, and 2% w/w), and time (1, 3, 6, and 9 month incubation).The treatments in this experiment were zero (B0), 0.5 (B1), 1 (B2) and 2% (B3) of biochar and zero (control) (D0), 0.5 (D1), 1 (D2) and 2% (D3) of palm leaves (zero, 18, 36 and 72 ton/ha, respectively) in three replications. Biochar were in powdered form and evenly added to soil (air-dried and passed through a 4 mm sieve) and incubated for 2 months.
Results: The results showed a significant difference (P