Iranian Water Research Journal

Abstract Estimating the correct volume of sediment in alluvial rivers plays a crucial role in river engineering, water resources, structures, facilities, water and environmental projects. Using the observed records of sediment load is the most reliable way in estimating the volume of sediment. Because of user unfriendly measurement tools and its remarkable fluctuation within the river section, sediment sampling is really difficult and needs highly experienced operators. In addition, it is a costly and time consuming practice.‎ Because of these limitations, frequency of sediment observation has decreased around the world, especially ‎in developing countries and remote areas. Therefore, researchers considered some modeling ‎approaches based on diverse terrain attributes and ‏hydrological variables. Some physically-based models such as the unit stream power (USP) theory of Yang, the SHESED model of Wicks and Bathurst are able to universally predict sediment yield of a watershed, but these models need lots of detailed information such as geological, hydraulic, and hydrological characteristics of the river basin that make them complex and costly. There is similar condition for process-based models such as the modified universal soil loss equation (MUSLE), introduced by Williams, and its family (USLE and RUSLE). Therefore, some simpler models were developed by researchers which are based on many simplifying assumptions and empirical relationships, especially for rainfall and runoff erosive effects. These models can be employed in areas with few data that result in high uncertain results. Application of data-driven ‎models such as different techniques of artificial intelligence are the ‏alternative method to the previous models. Artificial neural network (ANN) is one of the most ‏famous and strong data-driven technique that has been proved to be practical in modeling non-‎linear systems or complicated hydrologic processes such as sediment transport. Also, conventional sediment rating curve (SRC) has been widely used all over the world. Although these methods might be similar in some aspects, but each of them has its own characteristics that make them different from the others. In the present study, we use combinations of the above tools in a new approach and a hybrid model was developed to utilize the quality of each method in estimating the bed load sediment in the Yazdakan gauging station, simultaneously.
For the present study, Yazdakan Bridge gauging site (38.476724o, 44.798362o) located on Ghotorchay River was studied. The ‎Ghotorchay‎ River located in the Aras catchment ‏with an area ‎of 3471.9 km2 is a river ‎in West Azerbaijan province of Iran. It arises in the northwest of the Zagros Mountain range in Turkey. The total length of Ghotorchay‎ main streams in Turkey before entering to Iran reaches to 115 kilometers.‎ It flows from the border of Iran and Turkey at the height of 290 m from west to east through lands with steep slopes and passes the length of about 70 kilometers to reach to the Khoy city of West Azarbaijan. After leaving Khoy, the river turns north and flows through Evaghly valley where joins to the Zilber Chay river and extends until ‎meets the Agh Chay river at Marakan county. The river with its first name on Farhadi border outpost connects to the Aras ‎river. ‎
For current study, 133 paired data of flow discharge and corresponding bed load sediment were considered from the Yazdakan Bridge gauging site. The duration of collecting data started from January of 1999 to September of 2009 that measured by West Azarbaijan regional water authority. Monthly data of bed load sediment and discharge related to the time of the experiment were recorded. For constructing each model the data set was divided into two groups which the first 25% of paired date as group one was utilized for testing and the second group, including 75% of paired data employed for both training and validation of models.
In this study, discharge flow data were utilized as input for each of ANN and the sediment rating curve (SRC) techniques, separately to estimate ‎bed load sediment. An idea to optimize the results of ‎the SRC by ANN, navigate the author to a hybrid model made ‎from both of the techniques which called HAS in a way that the error of SRC was predicted using ANN.
Finally obtained results demonstrated that the results of HAS model is in good agreement with the observed ‎bed load sediment concentration ‎values; which depict better results than SRC and ANN models. For example, the calculated root ‎of mean square error for HAS model is 213.44 ton/day, while it is 262.028 tons/day and ‎‎238.305 tons/day for ANN and SRC models, respectively. In general, it is illustrated from the ‎results that the HAS hybrid model presents better performance than SRC and ANN for estimating bed load sediment in Ghotorchay River.

Abstract Increasing human population and reduction in land available for cultivation are two threats to agricultural sustainability. So, the biggest issue globally for agriculture is the need to produce enough to feed the growing world population. Another challenge is soil salinity. Soil salinity is an enormous problem for agriculture under irrigation. Millions of hectares of land throughout the world are too saline to produce economic crop yields, and more land becomes nonproductive each year because of salt accumulation. Irrigation in these areas causes the salts leached from the soils to build up in groundwater. Eventually, the groundwater table rises bringing saline water to the surface and making soils unsuitable for cultivation. Lack of proper drainage system leads to salinity in the soil and salts tend to accumulate in the upper soil profile. According to experimental and field evidence, subsurface drainage is the essential intervention to maintain a suitable growing environment for crops. According to previous studies the design criteria of the drainage system are too conservative and can be modified. So the main objective of this study is to use the experimental model for designing drain depth that can maintain desired salt concentration at the base of the root zone with less discharge water as compared with conventional drainage design equation.
Experiments were performed in a box with 1.8 m length, 1m width and 1.2 height. Drain depths were 20, 40 and 60 cm below the surface and the spacing was 180 cm. A separator layer (filter layer) was used on the surface of the drain tube to prevent fine soil particles from leaving the box into the drain tube. The impervious bottom layer was designed in the model. The surface-irrigation system was designed for irrigation from the top of the soil box. Saline groundwater prepared by mixing NaCL salt with fresh water. The electrical conductivity of groundwater was around 65 dS/m and the irrigation water salinity was around 0.321 dS/m. Irrigation flow rates were 0.14, 0.11 and 0.07 l/s. The observation piezometers were installed between lateral drains at different depths and with spacing of 15 cm from each other to monitor the Spatio- temporal variations of groundwater salinity. Groundwater samples were collected from piezometers that installed on different distances and depth and the samples of drain outflow were collected with time intervals of 5 to 10 minutes for electrical conductivity analyses. The electrical conductivity measured by the Senso Direct Con 200.
The results showed that there was a hydraulic gradient around the drains decreasing towards the midpoint. As expected, there was a reduction of electrical conductivity in time. The results also showed that the irrigation water mixed with the groundwater and was diluted because the salt was removed by drain tubes. So, the electrical conductivity was lower near the drain tubes and highest at the bottom of the box, as this effect was apparent during the experiment. The rapid decreasing of groundwater electrical conductivity was due to less saline irrigation water that entered the saline groundwater enhanced salt to the drain tubes. However, the results convincingly demonstrate significant differences in the rate of salt fall at different irrigation flow rates. The results showed that the high irrigation flow rate has greater potential for salt removal from groundwater during the experiments. In addition, drain depth affected the water table depth and had more effect on the salinity of the drain water. The electrical conductivity of drainage water for drain depth of 60 cm and irrigation water of 0.14 l/s was 39.65 dS/m. However, the electrical conductivity of drainage water for drain depth of 20 cm and irrigation water of 0.07 l/s was 29.37 dS/m. The results demonstrate that the drain water concentrations decreased exponentially with time for all drain depths. At the end of the experiments, drain water concentrations were almost the same for all drain depths.

Increasing human population and reduction in land available for cultivation are two threats to agricultural sustainability. So, the biggest issue globally for agriculture is the need to produce enough to feed the growing world population. Another challenge is soil salinity. Soil salinity is an enormous problem for agriculture under irrigation. Millions of hectares of land throughout the world are too saline to produce economic crop yields, and more land becomes nonproductive each year because of salt accumulation. Irrigation in these areas causes the salts leached from the soils to build up in groundwater. Eventually, the groundwater table rises bringing saline water to the surface and making soils unsuitable for cultivation. Lack of proper drainage system leads to salinity in the soil and salts tend to accumulate in the upper soil profile. According to experimental and field evidence, subsurface drainage is the essential intervention to maintain a suitable growing environment for crops. According to previous studies the design criteria of the drainage system are too conservative and can be modified. So the main objective of this study is to use the experimental model for designing drain depth that can maintain desired salt concentration at the base of the root zone with less discharge water as compared with conventional drainage design equation.
Experiments were performed in a box with 1.8 m length, 1m width and 1.2 height. Drain depths were 20, 40 and 60 cm below the surface and the spacing was 180 cm. A separator layer (filter layer) was used on the surface of the drain tube to prevent fine soil particles from leaving the box into the drain tube. The impervious bottom layer was designed in the model. The surface-irrigation system was designed for irrigation from the top of the soil box. Saline groundwater prepared by mixing NaCL salt with fresh water. The electrical conductivity of groundwater was around 65 dS/m and the irrigation water salinity was around 0.321 dS/m. Irrigation flow rates were 0.14, 0.11 and 0.07 l/s. The observation piezometers were installed between lateral drains at

Abstract The weir is one of the most applicable structure for flow control and measurement in open channels. Accurate measurement of discharge in irrigation channels is vital for irrigation management. Weirs are designed as control sections for providing a unique relationship between the discharge and water head. In this study, theoretical and experimental characteristics of flow through a weir located in a horizontal circular channel were investigated. Choosing of this structure is due to lack of adequate studies on governing hydraulic equations of this kind of channels and its practical characteristics. In this research, an equation was developed for estimating the discharge through the weir located at the end of a horizontal circular channel from a theoretical viewpoint, and then calibration of this theoretical discharge equation was done via the discharge coefficient. The experimental data obtained in this study were also used to develop an empirical discharge coefficient relationship.
The discharge equation of the circular weir ends up incomplete elliptic integrals of the first and second kinds, which are not very suitable for practical purposes due to their complexity. The theoretical discharge over the weir, Qt, can be expressed as:

where, F(a,b) is approximated using the method of undetermined coefficients as:

where g is the gravitational acceleration, h is the flow depth above the weir crest, D is the channel diameter, , , , and P is the weir height.
Introducing the discharge coefficient, Cd, yields the following equation for actual discharge, Q, of the weir:

Determination of discharge coefficient, Cd, needs measuring the actual discharge (experimental or field data). The experiments were performed in the hydraulic laboratory of the Irrigation and Reclamation Engineering Department, University of Tehran. In order to collect experimental data, the weir was installed at the end of two horizontal circular channels with nominal diameters of 200 mm and 300 mm, and numerous measurements of different parameters that may have effect on the discharge coefficient were carried out. An opening was provided on top of the pipes for flow head measurements by the point gauge. Water head over the weir crest was measured at a distance of 0.45 m upstream of the weir section. The weir plate was made of 10-mm-thick PVC sheet with a crest thickness of about 1 mm, and the downstream edge, beveled to a 45° angle (sharp-crested weir). For water heads over the weir crest smaller than 1.5 cm, in some cases clinging flow was occurring and thus there was no atmospheric pressure under the lower nappe. Though, for heads greater than 1.5 cm a clear lower nappe profile with atmospheric pressure underneath was formed. Effects of surface tension and viscosity forces on the discharge coefficient, Cd, became pronounced at low water heads. Viscous and surface tension effects on discharge coefficient are neglected in this research. This is owing to the operating range of the weir (minimum water head of 2 cm), which forbids surface tension effects and eliminates viscous effects. The experimental coefficient of discharge is computed for each data set collected in this study for known values of D, h, P and Q. A total of 350 tests were conducted to collect the data in the discharge ranges of 0.5 and 45 l/s. Suitable empirical equations for discharge coefficient were proposed using the 70% of the experimental data, and remaining data (30%) were used for validation procedure.
Using the curve-fitting technique, the following equation is obtained for Cd.

This empirical equation is valid for 0.095?h/P?1.8, 0.27?P/D?0.73 and 0.05?h/D?0.56. The assumptions made in deriving the above empirical equation of discharge coefficient are that the channel slope is horizontal, the flow is free and surface and viscous tension effects on Cd are negligible. A comparison of the experimental discharge coefficient with computed ones using the proposed empirical equation for all of the experimental data, the calibration data set and the validation data set showed that the computed discharge coefficient values are well within ±5% of the observed data for all three data sets. The average relative error of computed discharge coefficient using the proposed empirical equation for discharge coefficient Cd compared with the observed values is less than 5% for 95% of all experimental data. The results of this study reveals that a weir with low flow height is more sensitive to water flow depth, and weirs with more height are less sensitive to upstream flow head variation and thus are more reliable for flow measurement.

Abstract Water infiltration into the soil is one of the most important components of the hydrological cycle. Land use cover changes are affected by human-induced activities and growth socio-economic factors expansion of the forests, grazing, agricultural activities government policies and environmental factors such as drought. In the rural region, people encroach on forest areas for conversion to other uses, mainly cropland and rangeland though the land is not suitable for these purposes. The conversion of forests to other land uses may cause increase of water erosion, mass movements, and soil compaction by trampling and alteration of the hydrology cycle, among others. The aim of this study was to analyze the effect of some land uses on the amount of water infiltration and parameters of some infiltration models in forests, rangeland and agricultural land uses. This research was conducted at Fandoghlou sylvan region, located in Ardabil Province, that districted by Namin, Astara and Hir counties (38?, 10? to 38?, 30? East and 48?, 30? to 48?, 45? North). The acreage of the study area is about 16000 hectares. The Fandoghlou forest region is a continuance of Gilan semi tropical forest. The elevation in the catchment ranges between 1500 and 1850 m, and average of annual precipitation was recorded 290.4 mm by Ardabil synoptic station. Water infiltration experiments were conducted in the Fandoghlou region of Ardabil using double ring infiltrometer in forest, pasture and agricultural land uses in three replications. Totally 9 experiments were carried out in saturated state. Experiments were continued until at least 3 consecutive head fall data of double ring infiltrometer have been constant. Minimum time of infiltration experiments were 120 min. Initial water content was measured before water infiltration tests beginning, that amount of water content in forest land use was more than that measured in pasture and agricultural land use. A disturbed soil sample was collected from each different land use to measure soil physical and chemical properties. The organic carbon percentage was measured by the organic carbon oxidation method. Bulk density and saturated hydraulic conductivity were determined by the core method (Undisturbed soil samples were taken with steel core samples of 98.125 cm3). Soil pH and Electrical conductivity were measured by a pH and a conductivity meter. In this study, water infiltration rate was estimated using the five infiltration models including Philip, Kostiakov, Kostiakov-Lewis, Green-Ampt and Horton. To determine the best model among mentioned models in each land use, three statistical parameters RE, RMSE and R² were used. Results showed that for three land uses, including forest, pasture and agriculture, the Kostiakov-Lewis (RE, RMSE and R² were equal to 1.614, 0.023 and 0.9119, respectively), Green-Ampt (RE, RMSE and R² were equal to 2.824, 0.056 and 0.9196, respectively) and Philip (RE, RMSE and R² were equal to 2.901, 0.046 and 0.8408, respectively) models with less statistical error are the best models for infiltration rate simulation, respectively. Minimum and maximum amount of A parameter of Philip infiltration model in pasture (0.179) and forest (0.2) land uses, S parameter of Philip infiltration model in forest (0.472) and pasture (0.1.486) land uses, a parameter of Kostiakov infiltration model in pasture (0.682) and forest (0.821) land uses, k parameter of Kostiakov infiltration model in forest (0.547) and pasture (1.347) land uses, a parameter of Kostiakov-Lewis infiltration model in pasture (0.217) and agricultural (0.379) land uses, b parameter of Kostiakov-Lewis infiltration model in forest (0.011) and pasture (0.044) land uses, c parameter of Kostiakov-Lewis infiltration model in pasture and forest (0.23) and agricultural (0. 21) land uses, A^' parameter of Green-Ampt infiltration model in forest (8.469) and pasture (66.966) land uses, B^' parameter of Green-Ampt infiltration model in pasture (13.188) and forest (14.516) land uses, k parameter of Horton infiltration model in pasture (4.514) and forest (11.23) land uses, were calculated.
Philip and Green-Ampt infiltration models have best closeness than other considered models in infiltration rate simulation, because both of them have physical base. Horton infiltration model at pasture and agricultural land uses had maximum statistical error and have an over-estimating on infiltration rate. In forest and agricultural land uses, Kostiakov-Lewis infiltration model has overestimated the infiltration rate and underestimated in pasture land use. In agricultural land use, Kostiakov infiltration model underestimated the infiltration rate and overestimated in pasture and forest land uses. Minimum sorptivity coefficient of the Philip infiltration model has been extracted in forest land use, because matric potential of this land use was less than pasture and agricultural land uses. The initial water content of forest land use was more than pasture and agricultural land uses. Maximum empirical (B) coefficient of the Philip infiltration model, also has been extracted in forest land use, that indicate in this land use soil structure was better than that of other considered land uses, because in forest land use the amount of organic matter was more than other studied land uses.

Abstract Nowadays, the need for countries to design water distribution networks and abundant costs of water transfer projects, lead us to use new and effective methods for designing and optimizing water distribution networks. Practically, designers use methods of trial and error, based on engineering judgment to find a suitable solution. Many researches have been conducted in the field of optimizing methods because traditional practices do not guaranty an approach to find optimized or even close to optimized answer. Choosing the appropriate system would be done using different approaches. One of these approaches, which has been used in the present study, is the Method of Linear Programming. In the practical method of this study, in compliance with the technical limitations, a water supply system will be optimized to prevent hydraulic patrimonial flows. Using this method, we can optimize all costs of the structures, including purchasing, implementation and maintenance, by making them Linear. Therefore, an objective function which represents the minimizing of the costs and Linear equations that represent the technical limitations were defined. Each Linear programming equation contains three basic steps, including Objective Function, Constraints (for example, suitable pressure range, standard velocity range and pipe diameter) and Decision Variables which, in this study, are defined for water supply systems. In the present study, this process was configured for a real water supply project. The design, which is studied in this research, is the water supply project to the rural area of “Behbahan Qala Madrese” that covers an area about 720 hectares. With regard to the existence of rivers, and also roads and farms in the area, the net cultivated area was estimated about 625 hectares. The distance between studying area and the nearest river (Kheirabad River) is about six kilometers. Then, by defining Objectives Functions, Constraints of issue and Variables in LINGO, the answers were optimized and the results were compared with various practical conditions. In order to define various practical conditions, ten scenarios were defined using traditional and trial and error based methods. These scenarios, before and after the installation of protective structures, were hydraulically implemented in WATER HAMMER and the results of costs of each scenario, separated into the purchase, implementation and operation were extracted. In the next step, similar to practical condition, optimizing results of LINGO model, including pumping system, pipe diameter, type and size of the protective structures were implemented in WATER HAMMER under two conditions, before and after implementation of protective structures. After that, the results of optimizing by LINGO were compared with the results of practical method. According to the obtained results, Linear Programming Method is capable to optimize all major parts of the implementation of the network’s branches. This method incorporates an approach with high potential for optimizing; in a way that the best pumping system will be extracted using pressure limits (between 20 to 100 meters of water column) and water velocity in pipes (maximum 1.5 meter per second), optimum diameter and with compliance with price limits of pumps, electricity and required system pressure (according to the topography of the land). In other hand, best protective structures will be chosen in order to prevent patrimonial hydraulic flows, including water hammer and/or negative pressure in water supply system. Eventually, hydraulic simulation was conducted by implementing the results of LINGO into WATERHAMMER. In this research, all three parts were simultaneously defined in the Objective Function and all restrictions were taken under consideration in order to optimize the entire system under the effect of pumping system, piping network and also protective structures on patrimonial flows. Using Linear Designing Method will prevent wastage of national resources in addition to improving design velocity and economic efficiency. The practical scenarios were defined by changing pipe diameter, pumps and protective devices, as a combination practical scenario number 10 which had the lowest implementation cost compared to other scenarios. However, comparing the results of the Linear Programming method with practical scenario indicated that the costs of implementation of the transfer line optimized by Linear Programing method had reduced 3.39% in piping sector, 17.34% in buying and installing the pumps, 2.74% in protective structures and finally 3.69% of total costs implementation of the transfer line optimized by Linear Programing method had reduced 3.39% in piping sector, 17.34% in buying and installing the pumps, 2.74% in protective structures and finally 3.69% of total costs

Abstract Due to widely used sprinkle irrigation systems, it is necessary to develop a model for estimating evaporation and wind drift losses. Many factors are effective on the amount of losses due to evaporation and wind in the sprinkle irrigation systems. These factors can generally be divided into two categories of climatic and the system parameters. The purpose of this study is the assessment of proposed equations by some former researchers (Montero et al., Trimmer, Frost and Schwalon, Keller and Bliesner) for estimating the evaporation and wind drift losses of sprinkle irrigation systems in the Sanandaj city. The standards ISO 7749-1 and ISIRI 8995-3 and single sprinkler method have been taken to determine evaporation and wind drift losses for 3 types of sprinklers (AMBO, ZM22 &.ZK30). The nozzle diameter of sprinklers were ZM22 (10, 3.5), AMBO (10, 7) and a sprinkler ZK30 (8, 3.5) mm. To supply sprinkler operating pressure a dry horizontal electro pump was used. The main pipe was of polyethylene with an outside diameter of 160 mm. The butterfly valve in the bypass pipe was used to adjust the pressure of the model. A sub main polyethylene pipe was used with a diameter of 50 mm and a length of approximately 120 m to convey water to the sprinkler. In this study a riser with 165 cm height was considered. Sprinkler pressure was measured at the point of the riser. This point was lower than the point of changing of riser diameter. This distance must be at least 10 times greater than the diameter of the riser. The discharge of sprinklers were measured by volumetric method. The studied zone was a gridded region with an area of 60 × 60 square meters. The studied zone was gridded by using plastic meter and wooden sticks (3m×3m), and water collecting buckets (with a height of 90 mm and internal diameter of 80 mm) were installed. The minimum test time was 1 hour. This investigation is performed to assess effect of different intensities of wind and pressure amount at 4 different system pressure (3, 3.5, 4 and 4.5 bar), at 2 types of wind speed (0-1.8 calm wind, 1.8-4.4 average wind) on water losses. On-site testing wind speed with a handheld anemometer at a height of about 2 meters were measured and temperature and relative humidity were measured by TESTO 615 device.
The results of linear regression showed that the results of methods of Montero et al.(2000) and Keller and Bliesner (1990) for 3 sprinklers ZM22, AMBO and ZK30 had significantly different from the measured losses due to evaporation and wind. Also, computational results of Frost and Schwalon were significantly different in both sprinklers of Ambo and ZK30 at 5 and 1% significant level, respectively and were not significantly different in ZM 22. In both ZM22 and ZK30 sprinklers, computed results by Trimmer (1990) method were not significantly different with measured losses due evaporation and wind, but in Ambo sprinkler was significantly different at 1% significance level. For all of three studied sprinkler, the Montero et al. (2000) equation overestimated the water losses due to evaporation and wind, but Keller and Bliesner (1990) method underestimated the losses. Also the results of Frost and Schwalon (1955) in both of Ambo and ZK30 sprinkler and Trimmer method in the Ambo sprinkler have underestimated the losses. Also, based on NRMSE, the accuracy of all models were weak to estimate losses due to evaporation and wind in all three studied sprinklers. Accuracy of the trimmer (1987) equation was at the border of moderate to weak for ZK30 sprinkler.
The results of evaluating the models’ accuracy have shown that the used models are not suitable for estimating the losses due to evaporation and wind for studying sprinklers in the fixed head sprinkle irrigation systems in the city of Sanandaj. The failure of studying models was because of lack of consideration of all effective climatic variables, system and hydraulic in estimating the losses due to evaporation and wind. Also an equation was proposed in this study for in estimating the losses due to evaporation and wind in Sanandaj city. The accuracy of the proposed equation was evaluated by NRMSE criterion. The NRMSE values for the proposed equation were in the range of 14 to 19 percent. Therefore, the accuracy of the proposed equation is good according to the classification of this index and it can be used for estimating the losses due to evaporation and wind in Sanandaj city.

Abstract Sedimentation in dam reservoirs is an important issue which requires to be considered within the operation life of the dam. In order to maintain long time storage in dam reservoirs, sediment removal from reservoirs is an essential issue. There are numerous methods to achieve this goal. One of the well known sediment removal methods is the hydraulic flushing. This method is classified into free and pressure classes. Pressure flushing is considered as an effective method in removing local accumulated sediments behind the dam and around the location of valves and turbines. During the flushing operation, water level in the reservoir creates pressure on the sediment, causing the removal of the sediment and after a while of flushing a funnel shaped crater is created in the vicinity of the bottom outlet opening. In this study, the effect of expansion of bottom outlet channel within the reservoir on the dimensions of the flushing cone were investigated from the hydraulics view point.
The experiments were conducted with a physical model of a rectangular box with 7m length, 1.4m width, and 1.5m height, consisting of three parts, namely the inlet of the model, the main reservoir, and settling basin. In the inlet of the model, the turbulence of the inflow is disappeared and a uniform flow enters the main reservoir. Since in pressure flushing, the water surface level inside the reservoir is constant during the operation, the water level is adjusted by using a spillway positioned in the inlet of the model during the whole procedure. The main reservoir of the model was 5m long and the sediments were placed within this part of the model. The sediment particles used were non-cohesive silica sediments with uniform size and with median diameter (d50) 1.15mm and geometrical standard deviation (?g) 1.37. In order to perform flushing, an outlet made of Plexiglas with the diameter of 5cm aligned with the central line of flow was used. To investigate the effect of the bottom outlet channel expansion within the reservoir on the dimensions of flushing cone, the experiments carried out with different discharges and water depths above the bottom outlet in different expansion size of outlet channel in constant sediment level of 20cm above the center of the channel. Also experiments in the same hydraulic conditions without channel expansion within the reservoir were conducted as control tests. To perform the experiments, first the Plexiglas tube was positioned in its place as the outlet channel. The model was slowly filled with water until the water surface elevation reached to a desired level. The bottom outlet was manually opened until the outflow discharge, become equal to the inflow discharge. After a while, the sediments were discharged with the water flow in very high concentrations through the outlet channel (sudden discharge) and a funnel shaped crater was formed in front of it. At the end of each experiment, the flushing outlet was closed in which the incoming discharge was set to zero, then water was carefully and slowly drained from the main reservoir. After the run of each experiment, the bed level of scouring was measured using laser distance meters with the accuracy of 1mm, and the volume of flushing cone was calculated by Surfer 10.0 software. In order to investigate the hydraulics of the flow, the measurement of flow velocity in the flow rate of 3 liters per second and reservoir water level of 47.5cm for three expansion sizes of outlet channel (10, 20, and 30cm) was performed. The flow velocity measurement was done using an Acoustic Doppler Velocimeter with a sampling rate of 200 Hz. This device is capable of measuring moment velocities in three directions (velocity in directions x, y and z are u, v and w, respectively).
Results showed that, the expansion of bottom outlet channel within the reservoir has positive effects on the dimensions of the flushing cone. Therefore, the relative amount of bottom outlet channel expansion for 0.5, 1 and 1.5 times height of the sediments in the reservoir, leads to increase in flushing cone length for average of 48, 83 and 113% and flushing cone volume for average amount of 50, 74 and 96% compared to the case when the outlet channel is not developed. Using experimental results, two equations with good estimation are presented for calculating the flushing cone volume and length. Also, the results indicate that with increasing in the Froude number, sediment discharged from reservoirs increase, as in the higher expansion size of the bottom outlet, effect of the Froude number on the amount of the discharged sediment is high. The analysis of the flow hydraulics indicates that the flow velocity vectors while getting closer to the outlet opening, lose their expanded status and velocity gradient in the adjacent areas increases significantly. The analysis of the results for flow velocity measurements are presented in detail in this paper.

Abstract Stability of soil and water resources in agriculture, above all depends on the type of resource utilization and cropping pattern. Nowadays, maximization of factors such as income, job opportunities and minimization of costs as the economic and social aspects along with the limitations of arable land and water has attracted the attention of planners and managers of agricultural projects. One of the most important questions is the issue of sustainability, how to evaluate, measure and analyze sustainability? One of the methods to assess the stability is mathematical programming approaches. Application of this model for agricultural planning has a long history and a wide range. But using a particular type of this model to assess the sustainability, means the fractional model is a new topic. Lara and Stancu-Minasian (1999) examined the theoretical aspects of this model in a research titled as “Fractional programming: A tool for the assessment of sustainability”. As mentioned above, there are three main objectives for sustainable crop pattern, maximization of income and job opportunities and minimization of costs (In this case water consumption). Using fractional programming provides the possibility to make three goals in two goals which include maximization of “the net profit/water consumption” and “making job opportunity/water consumption”. In this way, the number of solutions is lower and therefore the decision-making process is easier. Fractional programming for planning and optimization cropping pattern has not been done yet. This paper is being studied to evaluate the stability in the agricultural systems of Bajestan plain located in the Razavi Khorasan province; and also determine the best cropping pattern. There are about 10,000 hectares of agricultural lands in the Bajestan plain. These lands are cultivated in seven major crops which include barley, saffron, wheat, pistachios, cotton, pomegranate and melon. Now the area under cultivation of these crops is 2250, 1630, 1500, 1400, 1200, 1350 and 670 hectares, respectively. In this region, about 70% of the working population are employed in agriculture.
To verify the effectiveness of the fractional models first of all, three mono goal linear models were prepared. The goal of each of these three models was maximization income and maximization of job opportunities and minimization of water consumption. By solving these models, three cropping patterns A1, B1 and C1 were obtained. For combination the triple dimensions of social, economic, and environmental, two relative criteria have been explained as the indications to evaluate system stability. Thus, in the next step, by dividing each of the two functions (maximization of income and maximization of job opportunities) to water consumption, two new objective functions were obtained in the form of fractional model. In fact, these two models represent two sustainability index. By solving those models, two cropping patterns A2 and B2 were obtained. Finally, an ideal fractional/mathematical programing model was prepared in which the last two functions were optimized. Optimization in relationships “the net profit/water consumption” and “making job opportunity/water consumption” leads to the new copping pattern (C2).
In optimized cropping pattern the area of barley, saffron, wheat, pistachios, cotton, pomegranate and melon obtained 111.4, 1608, 110.8, 7202.3, 103.1, 404.8 and 159.5 hectares, respectively. With the aim of maximizing the net profit, two relative criteria (“the net profit/water consumption” and “making job opportunity/water consumption”) in fractional model to the linear model increased 17.3% and 19.0%, respectively. With the aim of maximizing “making job opportunity”, two relative criteria in fractional model to the linear model increased 25.2% and 22.1%, respectively. In multi-goals programing approach, two relative criteria in fractional model to the linear model increased 32.4% and 42.5%, respectively. Overall, the ratio of income to water consumption in three cropping patterns of linear programming (A1, B1 and C1) was lower than three cropping patterns of fractional programming (A2, B2 and C2). The values are 17.8%, 26.7% and 33.3%, respectively. Also, the ratio of making job opportunity to water consumption in three cropping patterns of linear programming (A1, B1 and C1) was lower than three cropping patterns of fractional programming (A2, B2 and C2). The values are 18.9%, 22.1% and 42.5%, respectively. It can be concluded that fractional models in terms of both sustainability indices are superior to the linear models. These results are consistent with previous results and confirm them, such as Castrodeza et al. (2005), Maros et al. (2009), Hu et al. (2010) and Sabaghi et al.

Abstract Today, climate change has effect not only on the management levels of water resources, but also has some implications in everyday life. Study of changing in key variables of temperature and precipitation with regard to the effects of climate change in coming years can be helpful for solving some problems such as drought and sudden floods. Since others researchers have performed their analysis more than one stationary and just had to show changes in quantity, in this study, we try to consider it by location (region). As well as increasing the number of models and downscaling techniques and the future simulation of periods due to increased uncertainty in the results of climate change, in this study, only a regional model and a downscaling method were used. The purpose of this study is to investigate the effect of climate change on precipitation changes and extreme rainfall events in the next period (2040-2011) in two selected stations in Golestan province. In this study, the data obtained from the database of the Climate Research Unit (CRU), under four emission scenarios A1, A2, B1 and B2 were used. The HADCM3 regional model was used as boundary conditions. This model was released in the fourth assessment report (2007) and widely used for studies around the world. Precipitation data of two weather stations, including Ali Abad Katoul and Mazrae Nemooneh Artesh, as representative of both humid and semi- arid stations in Golestan province, were downscaled by proportional method. Then precipitation data were interpolated using IDW (8) as a statistical method, and finally the time series scenarios of future climate change were calculated by the change factor method. To investigate the number of occurrences of heavy rainfall, the precipitation index greater than 50 mm was considered and for specifying high-risk months in each station, the incidence of extreme rainfall was predicted.
The results show that precipitation changes for both stations in autumn, early spring, winter and late and mid-summer increases. The maximum rainfall in November and January are expected that warns the increased intensity of floods at the beginning of winter. At Aliabad Katoul station with a humid climate, precipitation changes for A1 scenario will occur with more intensity and also more precipitation during autumn and early winter and late summer would be expected. In the most of considered scenarios, increase in seasonal rainfall in the regions is expected in all seasons. The largest increase in precipitation in both stations occurred under the B2 scenario. The number of extreme events is expected will be increased in future periods, as this increase in precipitation of the Ali Abad Katoul station will be happening in late summer and early fall, but in Mazrae Nemooneh Artesh station will be happening in late autumn and early winter. Also, it is expected that the extent precipitation will increase in the future and the highest increase in Aliabad and Mazrae Nemooneh Artesh stations would happen in November and January, respectively. The number of extreme rainfall events (greater than 50 mm) and high precipitation levels increased in both stations; however the rate of average precipitation did not show significant changes. As a result, it can be concluded that the probability of occurrence of more heavy rainfall is high in both of studying stations.
Analyzing the results of the base period 2010 -1981 and the future period 2011 -2040 showed increasing in mean of annual precipitation of Ali Abad Katoul and Mazrae Nemooneh Artesh stations around 7.6 and 8.73 percent, respectively. Also, it is expected that the number of extent precipitation events will increase in future period. The results indicate that climate change could increase extreme events in Golestan province, so that by increasing levels of carbon dioxide, the number of days with precipitation will increase which leads to increase the frequency of flood events in the Golestan province.

station will be happening in late autumn and early winter. Also, it is expected that the extent precipitation will increase in the future and the highest increase in Aliabad and Mazrae Nemooneh Artesh stations would happen in November and January, respectively. The number of extreme rainfall events (greater than 50 mm) and high precipitation levels increased in both stations; however the rate of average precipitation did not show significant changes. As a result, it can be concluded that the probability of occurrence of more heavy rainfall is high in both of studying stations.
Analyzing the results of the base period 2010 -1981 and the future period 2011 -2040 showed increasing in mean of annual precipitation of Ali Abad Katoul and Mazrae Nemooneh Artesh stations around 7.6 and 8.73 percent, respectively. Also, it is expected that the number of extent precipitation events will increase in future period. The results indicate that climate change could increase extreme events in Golestan province, so that by increasing levels of carbon dioxide, the number of days with precipitation will increase which leads to increase the frequency of flood events in the Golestan province.

Abstract By development of urbanization in metropolitan and reducing permeable surfaces, problems occur during precipitation including the increase of runoff volume and high level of pollution in canals and streams. One of the modern and effective ways for management of urban runoff quantity and quality is the application of Best Management Practices (BMPs) which are widely used for reduction of non-point source pollution and runoff peak flow. BMPs for runoff consists of structural and non-structural types. Structural practices include physical measures and executive projects such as ponds, vegetated swales, bioretention cell systems, permeable pavements and infiltration trenches which are developed with the aim of runoff impacts reduction. Non-structural practices are the measures done through law enforcement and educational programs. The main challenge for designers and decision makers is the selection of optimum combination of practices among various available alternatives. The best choice should be cost effective, accessible and executable in the specified region. The aim of this research was to determine the best choice of scenario for urban runoff pollution reduction which is cost-effective. In this regard, Strom Water Management Model (SWMM) was used to assess the defined scenarios and BMPs which are applied in a subbasin of Tehran metropolitan. Strom Water Management Model (SWMM) is a dynamic model used for simulation of precipitation- runoff i.e. water quantity and quality of runoff from a precipitation event and long-term simulation of runoff in developed urban areas. The practices used in this study include four systems of vegetated swales, bioretention cell systems, permeable pavements and infiltration trenches. Vegetated swales are wide shallow channels that are covered by plants and are designed to slow down the runoff and increase the infiltration and pollutant removal while directing the runoff. Permeable pavement consists of a permeable surface that provides infiltration and storage of runoff and a pavement for traffic. Infiltration trench is a drilling groove that is filled with crumbs and forms a subsurface pond. Bioretention cells systems consist of a biological surface layer, a soil sand layer and retention layer which applies the chemical, physical and biological features of plants, microbes and soil for pollutants removal from runoff.
Using SWMM model critical subbasins are identified and the effectiveness of BMPs are assessed. Afterward, scenarios are defined based on the acquaintance gained about the performance of subbasins and BMPs through modeling and sensitivity analysis. For water quality simulation in the model, total suspended solids (TSS) and chemical oxygen demand (COD) are selected. For the case study region, four types of landuses, including residential with low and high density, street and highway are defined. Return periods for the flood are considered 2, 10 and 100 years. Dynamic wave method was used in hydraulic routing and Horton method was used for modeling the infiltration. The soil type of the case study area was sandy loam and its parameters such as hydraulic conductivity and permeability were necessary for Horton method. To model the pollutant washing Event Mean Concentration method (EMC) was used. The basic value and the range of EMC for TSS and COD were chosen from EPA report and literatures. To determine the best combination of BMPs in subbasins, various scenarios are defined. In this regard, firstly six basic scenarios, including five structural and one non-structural BMPs were applied in sensitive subbasin to assess their effectiveness in runoff peak flow reduction and pollutant removal. Afterward, 15 scenarios were defined based on the previous six scenarios and their combinations. The scenarios were simulated in SWMM and the results were assessed and compared based on an index defined as the ratio of percent removal to the cost of scenario. This index was called optimality index which shows the cost effectiveness of each scenario.
The results showed that applying these BMPs can cause a considerable reduction in runoff flow and pollution load. The subbasins characteristics which have the greatest impacts on runoff water quantity and quality are three factors, including surface permeability, percent of runoff routing to the pervious surface and land use. The first two factors are used in designing and defining the non-structural BMP. Thus, increasing these two quantities are suggested as applying non- structural practices. The third factor (landuse) is used for determination of critical subbasins. Comparing the results of BMPs performance using the optimality index showed that the infiltration trenches have a better performance due to higher optimality index. Also in the scenario that the combination of all four structural BMPs were used, 70% of TSS removal with the cost of 16.4 billion Rials was obtained. In general, the BMPs that have a higher optimality index, like infiltration trenches, have a better performance, but the executive factors and the existence of suitable space are involved as limiting factors.

Abstract Random-like behaviors in various natural phenomena led researchers to apply more accurate forecasting methods. While statistical models are more traditional to use for such complex behaviors, Chaos theory has been emerging as a new way to hydrologists and water engineers. In the Chaos theory viewpoint, random-like behavior can be related to a simple determinism which is hidden in the background of system dynamics and can be shown in an optimized phase space. If the conditions of a chaotic system which Chaos theory has been stated dominate the system behavior, dynamics in the phase space follows a fractal pattern which is aforementioned hidden determinism and called the attractor. The case study is the Kashkan River, which is located in Lorestan province, southwestern of Iran, where semi- arid climate is predominant. While the average number of dry days reach to 185 in a year, average precipitation is 375.3 mm during a water year. In the present study, the daily runoff time series of the Kashkan River have been analyzed using Chaos theory, following its observed random-like behavior. To perform chaotic analysis, a phase space should be reconstructed by determining optimize time delay and embedding dimension. So far, various methods have been suggested to calculate the time delay, including the Average Mutual Information method which have gained more popularity among the others. In this paper, a new method has been presented to estimate optimum time delay in the base of the AMI method. Therefore, instead of using the first local minimum of Mutual Information Function, its overall minimum has been considered to estimate optimum time delay. This method has been applied to daily runoff time series of the Kashkan River and its efficiency has been studied in fractal dimension estimation methods. While False Nearest Neighbors and Correlation Dimension methods have been employed to evaluate fractal dimension of system attractor, sensitivity to initial conditions have been studied using Lyapunov Exponent and Kolmogorov Entropy methods as the other major feature of chaotic behavior.
In the first part of this study, the AMI method and Mutual Information Function have been examined theoretically by evaluating its performance in a chaotic map called Rossler Map. It has been shown that the first minimum of MIF can be an optimum option to form best illustration of system chaotic attractor. While the first local minimum is more effective to mathematical functions such as RM, some other issues should be considered when the case study is a natural system, the MIF can have many minimums in different local sections. As mentioned earlier, the overall minimum of MIF have been used to determine the time delay as a new method phase space reconstruction which is obtained ? =107 days. False Nearest Neighbors and Correlation Dimension method have been used to evaluate fractal dimension, which showed the existence of a fractal attractor in phase space, and also the superiority of this new method for phase space reconstruction. Positive Lyapunov Exponent is a sign of sensitivity to initial conditions and therefore, chaotic behavior in system, which is more emphasized by calculating Kolmogorov Entropy in 3 different radius. Regardless of the selected radius, KE reaches to a finite number which is an evidence of chaotic behavior. While a certain number can not be calculated for Kolmogorov Entropy, it can be observed that by selecting a smaller radius, KE reaches to a finite positive number. Hence, the system entropy is consistent and follows a chaotic pattern.
Results indicated Chaos existence in this time series and suitability of Chaos theory-based models for governing system of flow in the Kashkan River. Sensitivity to initial conditions and fractal attractor as two major characteristics of chaotic system have been observed. In addition, a new AMI-based method to determine the optimum time delay has been showed better indication of system chaotic behavior in phase space. Compared with a traditional approach, the attractor which has been formed in reconstructed phase space behaves more constantly by increasing the embedding dimension in both FNN and CD methods. In comparison to similar studies analyzed the times series with different lengths, it can be concluded that the length of a time series cannot effectively adjust overall conclusion in the chaotic analysis of the Kashkan river flow governing system. Generally, evidences of chaotic behavior in the Kashkan river flow time series have been confirmed. Hence, employing chaotic models can be very helpful to forecast these time series.

Abstract Water is becoming a scarce and precious resource all over the world. Nowadays, irrigation has allocated 69 percent of the 3240 cubic kilometers of human consumed water and 87 percent of the total consumed water. Transformation of dry lands into irrigated areas with correct operation, reasonable utilization and good maintenance could be greatly effective on increasing of human needed products. Accomplished fact, all over the world is that most of operating irrigation and drainage projects don’t redound to objective points and not only they couldn’t successfully increase efficiency, but they also cause a reduction in production levels by harmful effect on aforesaid resources. Reasons have almost been incorrect design and operation, unsuitable and insufficient utilization and maintenance and generally poor management in different sketches. Ghoorichay reservoir dam is located in Ardabil province. This earth dam has clay core and storage capacity of this structure and usage volumes are 18.07 and 17.71 cubic million meters, respectively. Ghoorichay irrigation and drainage network is situated downstream of the dam, which covers 2200 ha area. Water is drawn from the reservoir and distributed through the main canal and many secondary channels to farms. Main canal is established along the kilometers, 13+347 to 20+317, to convey and distribute water into 4 secondary channels named LC1, LC2, LC3 and LC4. This canal has 6.97-kilometer length, after LC1 turnout from kilometer 13+347 to 15+093 it is generated with trapezoidal cross section, 0.001 slope and 2.25 cubic meters per second discharge. This section of main canal has 1.2 meter wide, 1 meter height and bank slope 1:1.5 (V:H). In this section of the main canal, normal depth is considered 0.75 meters, free height 0.25 meters and normal flow velocity is 1.3 meters per hour.
In this study, the first step to calibrate the gates is to choose the suitable place for flow measuring. So LC2 channel with 6- kilometer length and 20 turnouts considered the most important secondary channel in Ghoorichay irrigation and drainage network, is chosen and one of its slide gates with 1.15 meter width is assessed. It is necessary to notice that the chosen point for measurement should be in a location with minimum swing and wave ruffling to decrease measurement errors in hydraulic characteristics such as water surface width and water depth. In addition, it shouldn’t be any other turnout close by measuring location in order to ignore water losses through the distance. Then, the needed condition for operation should be created. So, water depth behind regulation structures should rise up to FSL or Full Supply Level and keep constant by proper regulation while measuring duration. Under this situation, flow measurement in LC2 channel had done. The present structure at the entry point of channel for measuring discharge is 3-feet Parshal flume. Having measured depth and discharge parameters in specialized points of the channel and considering channel dimensions, turnout and regulator structures, flow condition simulates by hydrodynamic models Root canal and ICSS and results have gotten with 10 different turnout opening.
Considering the amount of off-taking in upstream of LC2 channel and downstream demand of this turnout, which is 600 liters per second, also with considering network efficiency equal to 80 percent and evaporation and head losses equal to 50 liters per second. After inputting data in models, simulation is done for one hour duration and discharge and depth amount is determined. In order to assess introduced hydrodynamic models, and after calibration of two models, this part is allocated to comparison of output results with measured results along studied reach. This comparison is included water depth in turnout and regulator location and simulated water depth along the studied reach. The comparison is accomplished by drawing figures and statistics survey of errors in different points. Finally, comparing the best coincidence of results obtained from each model, with observed condition, the proper model is chosen. Results show that in both simulation dates, 1391/3/20 with entry discharge equal to 0.95 cubic meters per second and 1391/3/21 with entry discharge equal to 0.79 cubic meters per second, calculated error in the hydrodynamic model Rootcanal is fewer and better coincidence with observed data is seen. Although the results show that for ICSS hydrodynamic model the parameters are equal to 5.14 and 4.71 centimeters, respectively, and for Rootcanal hydrodynamic model they are equal to 2.12 and 1.61 centimeters, respectively. These results show better performance of the Rootcanal model than ICSS model for simulation and estimation of flow parameters in irrigation canals.

Abstract In recent years, Iran has been facing severe droughts and water shortages, therefore crop water requirement determination is an important issue in designing and managing plans for coping drought condition and optimum operation of irrigation systems. Accurate estimation of evapotranspiration could provide enough crop water requirement and prevent water losses. One of the most accurate methods to measure evapotranspiration is using Lysimeter. Lorestan province and Khorramabad region have major share of chickpea (Cicerarietinum L.) production in Iran. The Chickpea is the most important crop in Lorestan province, which has more cultivation area compare to the other crops. However, so far no comprehensive research has been conducted to estimate the chickpea water requirement. Therefore, the aim of this research is estimating water requirement and different crop coefficients of chickpea in Khorramabad region.
This research was conducted in research farm of Lorestan Agriculture Faculty with a height of 1148 meters above sea level and cold semi-arid climate during 2013 to find chickpea (Cicerarietinum L.) water requirement and different crop coefficients. To achieve these aims, 4 drainable Lysimeters were selected that their diameter and height were 0.45 and 0.8 m, respectively. The crop density was 50 plants per m^2. These Lysimeters were made from polyethylene. Soil texture was silty loam. The soil moisture capacity was measured by a pressure plate. Soil moisture in the field capacity was 26.66 Wt% and at the permanent wilting point was 19.24 Wt%. Soil bulk density was also 1.289 gr/?cm?^3. In this research, the time and the volume of each irrigation was chosen regarding to soil moisture less than 70% of FC in which the crop is not exposed to any moisture stress. In order to provide drainage in each Lysimeter, 15 cm from the Lysimeter bottom was filled with coarse sand and the rest depth of the Lysimeter was filled with the mixed of soil and fertilizer. To provide the same growth conditions, Lysimeters were placed within a chickpea farm. The excess water of each Lysimeter was drained and measured using a calibrated container. The soil moisture before irrigation at depths of 30 and 60 cm were measured with a moisture meter (IDRG) using installed sensors in each Lysimeter. Evapotranspiration was calculated using the water balance equation. According to this principal, amount of moisture in the soil equal to the amount of water minus the drainage water. The potential evapotranspiration was determined at the same time using the four grass planted Lysimeters. By dividing the chickpea evapotranspiration by potential evapotranspiration, crop coefficients were obtained. The crop coefficient value was not fixed and changed during the period of vegetative growth. According to the proposed method of FAO, for the period of vegetative growth curve was plotted and obtained crop coefficient was applied to each growth stage. In this method, it is assumed that the crop coefficient is changing during plant growth from the beginning to harvest stage. Although this change is not linear, but the vegetative period is divided into four stages. At each stage of plant growth, this change happens in the specified line. With daily meteorological data (T_max, T_min, ?RH?_max, ?Rh?_min, U_2 and n) and FAO equation in this period, potential evapotranspiration was measured and the results were compared.
According to the results, the water requirement of chickpea was estimated equal to 438 mm. The potential evapotranspiration also was estimated equal to 554.2 mm. 10-day minimum and maximum evapotranspiration of chickpea were 80.35 and 19.44 mm/10days, respectively, which these were in the months of June and March. The average crop coefficient was 0.488 in the initial growth stages, leaf area index and transpiration rate by increasing plant growth and during development stage, the crop coefficient increased and reached to 0.955. In the middle stage of the biological activity of the plant, crop coefficient was increased to 1.083 that creating a constant curve for this period. For the final stage, crop coefficient of 0.37 was also obtained. At the end of the growing season and completing the ripening stage, the chickpea grain was harvested. The chickpea water requirement for Khorramabad region was estimated at 338 mm using Iranian Water Requirement Document whereas, by using Cropwat, the water requirement was estimated at 295.8 mm. The evapotranspiration estimated by the FAO Penman-Monteith equation was 4.8 percent less than the actual amount of water requirement. Therefore, the accuracy of this equation is acceptable for Khorramabad region. The average seed yield was 723 kg per hectare. According to the results of this research, it is recommended that the following information could be used for Khorramabad region: Crop coefficient 0.488, 0.955, 1.083 and 0.371 for initial, development, middle, and ending growth stages, respectively, and water requirement for chickpea obtained equal to 438.04 mm. Using the obtained information for Khorramabad region and similar areas in the country, optimal irrigation management of chickpea will be possible.

Abstract Today, irrigation systems management with efforts to maximize their efficiency under water shortage conditions is an important and critical challenge for agricultural scientists and irrigation engineers. Evaluation of irrigation systems is an analysis of irrigation systems based on the module in real terms during the normal work of the farm system. Evaluation of the performance of irrigation systems can illuminate weaknesses of different aspects of the system and make constructive suggestions for improving the studied system's performance presented in terms of management that can ultimately lead to increased irrigation efficiency. In this study, ten solid-set sprinkler irrigation systems were evaluated in Koohdasht plain located in western Iran. In the evaluation, information regarding topography, profile sources of water supply, pumping system, main pipe arrangement, irrigation interval and sprinkler type was gathered and analyzed. Then, on each of the farms, on the days of irrigation and before irrigation, undisturbed samples of various soil layers of the depth of 0-25, 25-50, 50-75 cm were taken to determine bulk density and field capacity (FC). In addition, disturbed soil samples were taken to determine specific weight and other physical and chemical properties of the soil. Before testing, the water uniformity distribution and soil moisture testing were conducted to determine soil moisture deficit (SMD). Moreover, in all the fields, hydraulic variables such as pressure and sprinkler flow were determined and pressure in sprinkler was measured using a barometer and Pitot tube. Furthermore, sprinkler flow was calculated using a stopwatch and a 20-liter gallon based on volumetric method. Taking into account the topography of the region, an area was chosen for conducting tests where medium pressure systems occurred. After choosing an appropriate test area, the area between two sprinklers by means of a tape measure and wooden nails was determined with 3 × 3 m grid spacing. After that, cans with a height of 12cm and an internal diameter of 9.6 cm were used to collect water and were placed at grid points. Next, sprinklers were set to begin work and after working for at least an hour, the water inside the scaled cylinder was measured and recorded. Water samples of each of the fields' irrigation systems were taken and transported to laboratories to determine their chemical properties.
Results from field tests of soil and water quality assessment showed that all the soil fields contain normal ECe and SAR. Water supply for all systems came from well shafts and based on Soil Salinity Laboratory and America's classification were without limitation. Almost all physical and chemical properties of soil and water evaluated on the farms have been within the limits set and have no limitation of usage for agricultural purposes. The average pressure in sprinkler output in only three systems was within the limited allowable range (4 bar) and the average pressure of other systems was more or less than the allowable limited range. The normal range of pressure changes should be less than 20 percent and exist only in two systems. Existence of dramatic pressure changes is due to a lack of suitable pumping system design and system leakage. Some performance indicators were used, including Christiansen’s coefficient of uniformity (CU), distribution uniformity (DU), potential application efficiency of low-quarter (PELQ), application efficiency of low-quarter (AELQ), wind drift and evaporation losses (WDEL), deep percolation losses (DP) and adequacy of irrigation (ADirr). The mean values of these parameters in the order mentioned were as follows: 70.84, 43.64, 46.85, 38.01, 8.77, 31.02 and 64.66%, respectively. The results showed that the coefficient of uniformity and distribution uniformity in the all of systems is less than the range recommended by Merriam and Keller (81%?CU?87% , 67%?DU?80% ). DU is a good indicator of the extent of the probable uniformity problem. If small amounts of DU, in all parts take adequate irrigation, it is a sign of deep water percolation losses. Although small amounts of DU are relative, generally less than 67 percent is unacceptable. In 4 out of 10 systems, complete irrigation took place. In the remaining systems, due to the phenomenon of deficit irrigation occurring AELQ values were equal to PELQ. Unsuitable design and implementation of the irrigation systems under investigation were recognized as the most important reason for low PELQ. Unsuitable pressure was recognized as one of the most important causes. Furthermore, simultaneous use of many sprinklers and using more than one sprinkler on laterals were considered as the most important reason for low water distribution.
Water and soil quality of Koohdasht plain lacked any problems. Physical and chemical properties of soil and water in all fields had a normal range and for irrigation did not set any limitations. The results indicated that solid-set sprinkler irrigation systems have low application efficiency and their uniformity of distribution is less than the amounts recommended by Keller and Merriam. In general, the results of this study showed that in many cases design and operation problems existed, but the major share of the problem of low performance of sprinkler irrigation systems in Koohdasht plain lay with weak management and exploitation of these systems.

Abstract Mountainous area has a considerable share in supplying water demand in the arid regions, because the snow consists a large part of the rainfall in such regions which could be saved in the area located in the high elevations for a long time. Therefore, snowmelt runoff consists a large part of the total runoff in the mountain watersheds. The snow hydrology is much complicated than rainfall hydrology, since there is always a lag time in occurring snowmelt runoff in the basins' outlet. Thus, finding out simple methods for calculating such runoff is so important. In this research, after calibrating and validating the critical temperature and degree-days coefficient, the HEC-HMS model was applied to simulate the snowmelt runoff in Karoun basin, which is one of the most important mountainous watersheds in Iran.
In this research, a large part of Karoun watershed up to PolShaloo outlet was selected. This region is located in the south-west of Iran, which lies between 50o23'37" to 51o54'29" E longitude and between 30o16'50.4" to 31o32'18.3" N latitude. In this area, about 50 percentage of total precipitation falls as snow and usually occurs during November-May. The HEC-HMS model was applied for runoff simulation. In this regard, first the whole basin was divided into eight sub-basins entitled Marghak, Barez, Pataveh, Kata, Solegkan, Armand, DazakAbad and PolShalou. Then, based on the Digital Elevation Mode, the sub-basins' physiographic characteristics were extracted in Arc-View environment and using HEC-GeoHMS extension. The values of curve number, lag time and initial loss were calibrated and validated for each of the sub-basins using the observed snow-free runoff events. Thereafter, the hypsometric maps with 100-meter elevation intervals were prepared. The snowmelt pattern was determined for each of the elevation bands by using hypsometric maps and the required thermal data. Moreover, the snow water equivalent was calculated in the first day of the selected snowy events based on the daily calculations of snowmelt. After providing the required input data, the HEC-HMS mode was run for the snowy events and the critical temperature and degree-day coefficient were calibrated and validated for the study area.
The hypsometric maps with 100-meter elevation intervals revealed that 22, 70 and 8 percent of the study area are, located in the areas with the elevation ranges of 693-2000, 2000-3000 and >3000 meter, respectively. Based on the observed data in the snow survey stations in the study area, the correlation coefficient between snow water equivalent and elevations was higher than 90 percentage. Therefore, this equation was applied for determining the snow water equivalent in the beginning of the selected snowy events. The daily calculations of snowmelt based on this equation showed that in the Mach 17, 1998, which is the first day of the first selected snowy event, all the regions with elevations higher than 1943 meter is covered by snow and the non-snow regions covers less than 20 percentage of the study area. The results of the sensitivity analysis of the HEC-HMS model for calibrating the basins' physiographic parameters in the non-snow events revealed that the curve number, initial loss and lag time parameters had the most effect on the outlet discharge. The calibrated values for these parameters ranges among 76.6-91, 5.02-13.96 millimeter and 155-571.12 minutes, respectively. After calibrating and validating the basins' physiographic parameters, the snowmelt parameters were calibrated and validated based on the observed runoff during March 17-19, 1998, which is one of the largest snowy event in the study area. In this stage, the results of the sensitivity analysis demonstrated that critical temperature and degree-day coefficient had the most effect on three characteristics of flood hydrograph, including the peak discharge, the average flood depth and the time of peak discharge occurrence. The increase in the critical temperature usually led to the peak runoff delaying. The exception was for Armand sub-basin due to its high area in which, the increase in the critical temperature, the peak discharge of the flood hydrograph was increased mainly due to increasing the snow melt rate and subsequently the flow rate. The best values for critical temperature and degree-day coefficient, through the calibration process, were obtained 2.5 oC and 3.2 millimeter per oC-day, respectively. Based on the calculated criteria indices in the validation process, applying these values led to the acceptable errors in estimating snowmelt runoff for the flood event occurred through March 25, 1998 to April 8, 1998.
The results of this research showed that among different physiographic characteristics, the curve number, initial loss and lag time parameters had the most effect on the average flood depth, the peak discharge and the time to the peak discharge for the non-snow events. Moreover, the snowmelt runoff is highly influenced by critical temperature and degree-day coefficient and therefore, the HEC-HMs results of simulating runoff in the mountain watersheds will be reliable if the suitable values are selected for these parameters. Based on the results of this study, 2.5oC and 3.2 millimeter per degree-days will be the best values for critical temperature and degree-day coefficient in the study area, respectively.

Abstract The streams can be divided into three groups; 1) Perennial streams, 2) Seasonal streams and 3) Ephemeral streams. Seasonal streams are the kinds of stream that have flowed in certain seasons and they often occur in the watershed due to snow melt or sudden rain. The flow in this type of streams, acts as a flash flood, consequently its flow hydrograph has a sharp peak and a relatively short base time and it can cause erosion and sediment transport in the watershed, which altogether create some problems and constraints to human. The purpose of this research is measuring the temporal changes of sediment transported (bed-load) by flash flood (unsteady flow condition) in a laboratory flume. The experiment canal that uses in this research has 10 m length, 30 cm width, and 50 cm height. Using an electrical device which is connected to the channel pump, input flow turns into an unsteady flow and then enters the channel. Some of the characteristics of this flow are imperceptible increase and decrease while passing through the laboratory flume. In this research, a new method is also presented for sampling and measuring the bed load sediment which is transported by the flow in the laboratory. In this method form of the canal is changed. We created five sections: 1) fixed roughness, 2) mobile bed load, 3) section of sampling, 4) fixed roughness and 5) glass. The sampler of sediment includes 20 net box with length, width and height 25 cm, 5 cm and 3 cm, respectively. For inscription date, use two camera system. One of them for record of bed change that set in front of mobile bed and another one for record boxes of sampler movement under the section of sampling. Time duration of sampling for each box of the sampler is between 3 to 6 second. A grading of sediment with D50=2.5 mm is used. This research includes a series of stream symmetric triangular hydrographs in different shapes and contains different base times (60 sec, 90 sec, and 120 sec) and peak flows (between 20 and 55 liters per second), which were crossed from the bed of sediment. Then the transported bed load, affected by them, was removed by using the produced sampler. Also, as base flow, two steady streams 0.95 and 1.5 liters per second is determined. The effect of some factors such as existence or lack of the base flow on amount of transported bed load were also checked and experimented by input stream hydrograph. The results show that maximum bed load transport decrease with stream of base flow and it is minimum at experiment without base flow. Also, a total of sediment transport is higher in the experiment with base flow. Therefore, the existence of the base flow can increase sediment transport and upstream erosion. In this experiment, the hydrograph had greater base flow, increase upstream erosion to 76.5 % and for another base flow they increase 26.5 %. For hydrograph with the same pick flow, when its base time increase 1.5 and 2 times, total sediment transport increase 45 and 92 percent, respectively. Also peak of sedigraph increase with base time and therefore base time is an important parameter for upstream erosion and sediment transport. In another part of this research, the effects of fixed bed roughness on characteristics of flow hydrographic in a channel is investigated. In this series of experiments, the fixed bed was made using three different roughness, including one roughness of glass and two roughness of different granulations. The results of movable bed show that bed slope has a great effect on upstream erosion and transportation of sediment to downstream. As increasing the bed slope from 0.005 to 0.01 lead to increase 50% of transported bed load and with two times the slope, the transported bed load increase to 400%. The results show that a temporal lag was found between the flow hydrographs peak and the sediment hydrograph peak. The temporal lag was found to be about 5 - 11% of flow hydrograph duration. For hydrograph with the same pick flow, average sediment transport decreases with increase the base time. Also elevation of bed load showed that the maximum erosion occurred at the start of bed load transmission

Abstract In order to provide more realistic representation of processes governing the water and energy balances as well as water quality and plant physiological processes, weather data are needed at finer timescales than currently are available in most regions. Air temperature is one of the critical variables that drives all biological systems, and is a fundamental input parameter for climatological and agricultural models (e.g. crop growth). However, for the application of agricultural models and for climatological studies, many of the available data consist of only the daily minimum and maximum temperatures. For many applications, it is often useful to obtain an approximation of subdaily data. In the literature, a variety of models with varying degrees of complexity have been developed to approximate diurnal temperature curves. The diurnal temperature variation has been modeled in a variety of ways that vary from simple curve-fitting models based upon sine, cosine and/or linear curves to more sophisticated models utilizing Fourier analysis and complex energy balance models. Although modeling approaches are different, most models are based on minimum (Tmin) and maximum (Tmax) temperatures. It is useful to have accurate temperature trend models that are not site-specific. However, most empirical models show variable results. This study aimed to derive the daily air temperature disaggregation parameters for some regions of Iran and to compare the performance of some daily-to-subdaily air temperature disaggregation models. For this purpose, air temperature disaggregation models, including WAVE I, WAVE II, WCALC, ERBS, ESRA, and TM models were calibrated and their performance was compared, using long-term daily and three-hourly weather data obtained from 12 different synoptic weather stations in Iran. The WAVE I method uses a cosine function assuming that the Tmax occurs at 1500. The WAVE II model uses a cosine function for the period from the time of minimum temperature to the time of maximum temperature and another cosine function from the time of the maximum temperature to the time of minimum temperature of the next day. The method is fixed at 1400 hours the time of the maximum temperature, and at sunrise the time of the minimum temperature. In the WCALC model, the day is divided into 3 segments: (a) midnight to sunrise + 2 h; (b) daylight hours; (c) sunset to midnight. The method assumes a change from night to day temperature at sunrise + 2 h, and the night temperatures are linear with time. In addition to the current day's Tmax and Tmin, the method requires the Tmax and Tmin of the previous day and the Tmin of the following day. The empirical Erbs model is a Location- and month-independent to explain the diurnal variation in daily temperature data. In this study, the daily average temperature and thermal amplitude were used instead of their corresponding monthly values since they were available. The TM model divides the day into three segments: (a) from the sunrise hour (Hn) to the time of maximum temperature (Hx), (b) from Hx to the sunset hour (Ho), (c) and from Ho to the sunrise hour for the next day (Hp). The model uses two sine-wave functions in the daylight and a square-root decrease in temperature at night. Hn and Ho are determined as a function of the site latitude and the day of the year. The time of the maximum temperature is set 4 hours before sunset. Temperature at Hn, Hx and Hp are the observed minimum, maximum temperature for the current day and minimum temperature for the following day, respectively. For the facility to use the daily data, the minimum temperature for the current day is used for the temperature at Hp. The temperature at time Ho is calculated with an empirical equation. The capability of the studied models for retrieving the measured three-hourly air temperature was evaluated, using root mean square error (RMSE) (?C), the mean error (ME) (?C), the mean absolute error (ME) (?C), Pearson correlation coefficient (r), and Nash–Sutcliffe model efficiency coefficient (EF). Different contributions to the overall error were decomposed using a regression-based method. The results indicated that the inversely estimated air temperature disaggregation parameters were in a reasonable physical range. Compared to the WAVE I, WAVE II, WCALC, ERBS, and ESRA models, the calibrated TM model had the best performance to disaggregate daily air temperature with EF, RMSE, and r ranging between 0.977–0.988, 1.059–1.808 ?C, and 0.983–0.994, respectively. Compared to air temperature disaggregation models with an arbitrary value for the time of maximum and minimum air temperature, the models in which the above mentioned times are described as a function of sunrise and/or sunset had better performance in describing the diurnal variations in air temperature. The use of the WAVE II model (with EF, RMSE, and r ranging between 0.966–0.984, 1.126–1.815 ?C, and 0.983–0.992, respectively) can be recommended for the regions with no subdaily weather data needed for calibration of the disaggregation models.

Abstract Groundwater resources in arid and semi-arid areas are the most critical resources for sustainable development and hence, protecting of these resources is essential. The yearly average decline of 0.44 meters in the groundwater level of the Broujen- Faradonbeh aquifer reflects the excessive abstraction of the plain aquifer. In this study, long term (1992-2011) piezometric data and water budget results were taken into account in evaluating groundwater resources using the WEAP model and then management actions were applied to protect the aquifer. Each of management actions was evaluated as a scenario in the WEAP model. All of seven considered management scenarios, including changes in cropping pattern, increase in efficiency of irrigation, and water withdrawal restriction with combining to each other were carried out in the WEAP model. The results showed that increasing in efficiency of irrigation by using modern irrigation systems, replacement of 25 to 50 percent of alfalfa and potato area with wheat cultivation would be useful adjacent to make restriction in groundwater withdrawal. The results also showed that the WEAP model has high capability in scenario development and assessmentGroundwater resources in arid and semi-arid areas are the most critical resources for sustainable development and hence, protecting of these resources is essential. The yearly average decline of 0.44 meters in the groundwater level of the Broujen- Faradonbeh aquifer reflects the excessive abstraction of the plain aquifer. In this study, long term (1992-2011) piezometric data and water budget results were taken into account in evaluating groundwater resources using the WEAP model and then management actions were applied to protect the aquifer. Each of management actions was evaluated as a scenario in the WEAP model. All of seven considered management scenarios, including changes in cropping pattern, increase in efficiency of irrigation, and water withdrawal restriction with combining to each other were carried out in the WEAP model. The results showed that increasing in efficiency of irrigation by using modern irrigation systems, replacement of 25 to 50 percent of alfalfa and potato area with wheat cultivation would be useful adjacent to make restriction in groundwater withdrawal. The results also showed that the WEAP model has high capability in scenario development and assessmentGroundwater resources in arid and semi-arid areas are the most critical resources for sustainable development and hence, protecting of these resources is essential. The yearly average decline of 0.44 meters in the groundwater level of the Broujen- Faradonbeh aquifer reflects the excessive abstraction of the plain aquifer. In this study, long term (1992-2011) piezometric data and water budget results were taken into account in evaluating groundwater resources using the WEAP model and then management actions were applied to protect the aquifer. Each of management actions was evaluated as a scenario in the WEAP model. All of seven considered management scenarios, including changes in cropping pattern, increase in efficiency of irrigation, and water withdrawal restriction with combining to each other were carried out in the WEAP model. The results showed that increasing in efficiency of irrigation by using modern irrigation systems, replacement of 25 to 50 percent of alfalfa and potato area with wheat cultivation would be useful adjacent to make restriction in groundwater withdrawal. The results also showed that the WEAP model has high capability in scenario development and assessmentGroundwater resources in arid and semi-arid areas are the most critical resources for sustainable development and hence, protecting of these resources is essential. The yearly average decline of 0.44 meters in the groundwater level of the Broujen- Faradonbeh aquifer reflects the excessive abstraction of the plain aquifer. In this study, long term (1992-2011) piezometric data and water budget results were taken into account in evaluating groundwater resources using the WEAP model and then management actions were applied to protect the aquifer. Each of management actions was evaluated as a scenario in the WEAP model. All of seven considered management scenarios, including changes in cropping pattern, increase in efficiency of irrigation, and water withdrawal restriction with combining to each other were carried out in the WEAP model. The results showed that increasing in efficiency of irrigation by using modern irrigation systems, replacement of 25 to 50 percent of alfalfa and potato area with wheat cultivation would be useful adjacent to make restriction in groundwater withdrawal. The results also showed that the WEAP model has high capability in scenario development and assessment

Abstract Drought phenomenon has significant effects on various aspects, especially in the arid and semiarid regions of Iran like as Yazd province. Drought conditions in an area has been evaluated using conventional indices. This research attempts to select an efficient index with regional applicability. According to related literature, appropriate index has been selected based on the objects and type of study. In this research, SPI has been identified as an appropriate index for study of groundwater condition during drought. Since the SPI was considered as an appropriate index for explaining the water resources condition, different time scales of the SPI were applied to check the correlation between SPI and the fluctuation of the water table in the study area. The results show high correlation between fluctuations of the water table in piezometers with SPI 12-month period. As a result, SPI 12-month is proposed as an appropriate drought index in the study area.

Drought phenomenon has significant effects on various aspects, especially in the arid and semiarid regions of Iran like as Yazd province. Drought conditions in an area has been evaluated using conventional indices. This research attempts to select an efficient index with regional applicability. According to related literature, appropriate index has been selected based on the objects and type of study. In this research, SPI has been identified as an appropriate index for study of groundwater condition during drought. Since the SPI was considered as an appropriate index for explaining the water resources condition, different time scales of the SPI were applied to check the correlation between SPI and the fluctuation of the water table in the study area. The results show high correlation between fluctuations of the water table in piezometers with SPI 12-month period. As a result, SPI 12-month is proposed as an appropriate drought index in the study area.

Drought phenomenon has significant effects on various aspects, especially in the arid and semiarid regions of Iran like as Yazd province. Drought conditions in an area has been evaluated using conventional indices. This research attempts to select an efficient index with regional applicability. According to related literature, appropriate index has been selected based on the objects and type of study. In this research, SPI has been identified as an appropriate index for study of groundwater condition during drought. Since the SPI was considered as an appropriate index for explaining the water resources condition, different time scales of the SPI were applied to check the correlation between SPI and the fluctuation of the water table in the study area. The results show high correlation between fluctuations of the water table in piezometers with SPI 12-month period. As a result, SPI 12-month is proposed as an appropriate drought index in the study area.

Drought phenomenon has significant effects on various aspects, especially in the arid and semiarid regions of Iran like as Yazd province. Drought conditions in an area has been evaluated using conventional indices. This research attempts to select an efficient index with regional applicability. According to related literature, appropriate index has been selected based on the objects and type of study. In this research, SPI has been identified as an appropriate index for study of groundwater condition during drought. Since the SPI was considered as an appropriate index for explaining the water resources condition, different time scales of the SPI were applied to check the correlation between SPI and the fluctuation of the water table in the study area. The results show high correlation between fluctuations of the water table in piezometers with SPI 12-month period. As a result, SPI 12-month is proposed as an appropriate drought index in the study area.

Drought phenomenon has significant effects on various aspects, especially in the arid and semiarid regions of Iran like as Yazd province. Drought conditions in an area has been evaluated using conventional indices. This research attempts to select an efficient index with regional applicability. According to related literature, appropriate index has been selected based on the objects and type of study. In this research, SPI has been identified as an appropriate index for study of groundwater condition during drought. Since the SPI was considered as an appropriate index for explaining the water resources condition, different time scales of the SPI were applied to check the correlation between SPI and the fluctuation of the water table in the study area. The results show high correlation between fluctuations of the water table in piezometers with SPI 12-month period. As a result, SPI 12-month is proposed as an appropriate drought index in the study area.

Abstract Determination of water requirements is an important parameter for optimum use of the available water resources in agricultural purposes. Some information about plant cover condition such as plant surface temperature and crop density over the entire area are necessary for accurate estimation of required water in the basin scale. Measurement of these parameters by traditional methods are very difficult and expensive. While estimation of the mentioned parameters by remote sensing (RS) techniques are very easy. Hence, in the present study, ground surface temperature in Hamedan province was determined by RS techniques. For this purpose, a set of 12 Landsat 7 ETM+ images during 1998-2002 were selected and the reflection coefficient of ground surface, ground radiation coefficient, vegetation indexes, such as NDVI were determined. Based on these indicators the surface temperature was estimated using the SEBAL (surface energy balance algorithm for land) algorithm and compared with measured data in meteorological stations of Hamedan province. Results indicated that there is no significant difference between the surface temperature estimated from remote sensing data and that reported by meteorological stations. Overall results showed that the SEBAL algorithm with a correlation coefficient of 0.75 and Root Mean Square Error (RMSE) of 5.4 c? had a high accuracy in estimating the ground surface temperature.

Determination of water requirements is an important parameter for optimum use of the available water resources in agricultural purposes. Some information about plant cover condition such as plant surface temperature and crop density over the entire area are necessary for accurate estimation of required water in the basin scale. Measurement of these parameters by traditional methods are very difficult and expensive. While estimation of the mentioned parameters by remote sensing (RS) techniques are very easy. Hence, in the present study, ground surface temperature in Hamedan province was determined by RS techniques. For this purpose, a set of 12 Landsat 7 ETM+ images during 1998-2002 were selected and the reflection coefficient of ground surface, ground radiation coefficient, vegetation indexes, such as NDVI were determined. Based on these indicators the surface temperature was estimated using the SEBAL (surface energy balance algorithm for land) algorithm and compared with measured data in meteorological stations of Hamedan province. Results indicated that there is no significant difference between the surface temperature estimated from remote sensing data and that reported by meteorological stations. Overall results showed that the SEBAL algorithm with a correlation coefficient of 0.75 and Root Mean Square Error (RMSE) of 5.4 c? had a high accuracy in estimating the ground surface temperature.

Determination of water requirements is an important parameter for optimum use of the available water resources in agricultural purposes. Some information about plant cover condition such as plant surface temperature and crop density over the entire area are necessary for accurate estimation of required water in the basin scale. Measurement of these parameters by traditional methods are very difficult and expensive. While estimation of the mentioned parameters by remote sensing (RS) techniques are very easy. Hence, in the present study, ground surface temperature in Hamedan province was determined by RS techniques. For this purpose, a set of 12 Landsat 7 ETM+ images during 1998-2002 were selected and the reflection coefficient of ground surface, ground radiation coefficient, vegetation indexes, such as NDVI were determined. Based on these indicators the surface temperature was estimated using the SEBAL (surface energy balance algorithm for land) algorithm and compared with measured data in meteorological stations of Hamedan province. Results indicated that there is no significant difference between the surface temperature estimated from remote sensing data and that reported by meteorological stations. Overall results showed that the SEBAL algorithm with a correlation coefficient of 0.75 and Root Mean Square Error (RMSE) of 5.4 c? had a high accuracy in estimating the ground surface temperature.

Determination of water requirements is an important parameter for optimum use of the available water resources in agricultural purposes. Some information about plant cover condition such as plant surface temperature and crop density over the entire area are necessary for accurate estimation of required water in the basin scale. Measurement of these parameters by traditional methods are very difficult and expensive. While estimation of the mentioned parameters by remote sensing (RS) techniques are very easy. Hence, in the present study, ground surface temperature in Hamedan province was determined by RS techniques. For this purpose, a set of 12 Landsat 7 ETM+ images during 1998-2002 were selected and the reflection coefficient of ground surface, ground radiation coefficient, vegetation indexes, such as NDVI were determined. Based on these indicators the surface temperature was estimated using the SEBAL (surface energy balance algorithm for land) algorithm and compared with measured data in meteorological stations of Hamedan province. Results indicated that there is no significant difference between the surface temperature estimated from remote sensing data and that reported by meteorological stations. Overall results showed that the SEBAL algorithm with a correlation coefficient of 0.75 and Root Mean Square Error (RMSE) of 5.4 c? had a high accuracy in estimating the ground surface temperature.

Abstract Agricultural development in Iran depends on the amount of water and knowledge of the seepage amount from the canals is required. Although there are many empirical equations for estimating seepage discharge from the canals, the coefficients of these equations are different for local conditions of Iran and also these equations vary in different areas. In this research, the ability of the Seep/W model was studied to estimate the seepage discharge from an assumed canal. Variable parameters in this study are the canal slope and hydraulic conductivity of soil. In addition, the hydraulic gradient, uplift pressure and seepage velocity are investigated in different condition. Results show that with decreasing in canal slope, seepage discharge increases linearly. The hydraulic gradient and seepage velocity are minimum in the center line of canal. Increasing of hydraulic conductivity, causes to increase seepage discharge from canal body, linearlyAgricultural development in Iran depends on the amount of water and knowledge of the seepage amount from the canals is required. Although there are many empirical equations for estimating seepage discharge from the canals, the coefficients of these equations are different for local conditions of Iran and also these equations vary in different areas. In this research, the ability of the Seep/W model was studied to estimate the seepage discharge from an assumed canal. Variable parameters in this study are the canal slope and hydraulic conductivity of soil. In addition, the hydraulic gradient, uplift pressure and seepage velocity are investigated in different condition. Results show that with decreasing in canal slope, seepage discharge increases linearly. The hydraulic gradient and seepage velocity are minimum in the center line of canal. Increasing of hydraulic conductivity, causes to increase seepage discharge from canal body, linearlyAgricultural development in Iran depends on the amount of water and knowledge of the seepage amount from the canals is required. Although there are many empirical equations for estimating seepage discharge from the canals, the coefficients of these equations are different for local conditions of Iran and also these equations vary in different areas. In this research, the ability of the Seep/W model was studied to estimate the seepage discharge from an assumed canal. Variable parameters in this study are the canal slope and hydraulic conductivity of soil. In addition, the hydraulic gradient, uplift pressure and seepage velocity are investigated in different condition. Results show that with decreasing in canal slope, seepage discharge increases linearly. The hydraulic gradient and seepage velocity are minimum in the center line of canal. Increasing of hydraulic conductivity, causes to increase seepage discharge from canal body, linearlyAgricultural development in Iran depends on the amount of water and knowledge of the seepage amount from the canals is required. Although there are many empirical equations for estimating seepage discharge from the canals, the coefficients of these equations are different for local conditions of Iran and also these equations vary in different areas. In this research, the ability of the Seep/W model was studied to estimate the seepage discharge from an assumed canal. Variable parameters in this study are the canal slope and hydraulic conductivity of soil. In addition, the hydraulic gradient, uplift pressure and seepage velocity are investigated in different condition. Results show that with decreasing in canal slope, seepage discharge increases linearly. The hydraulic gradient and seepage velocity are minimum in the center line of canal. Increasing of hydraulic conductivity, causes to increase seepage discharge from canal body, linearlyAgricultural development in Iran depends on the amount of water and knowledge of the seepage amount from the canals is required. Although there are many empirical equations for estimating seepage discharge from the canals, the coefficients of these equations are different for local conditions of Iran and also these equations vary in different areas. In this research, the ability of the Seep/W model was studied to estimate the seepage discharge from an assumed canal. Variable parameters in this study are the canal slope and hydraulic conductivity of soil. In addition, the hydraulic gradient, uplift pressure and seepage velocity are investigated in different condition. Results show that with decreasing in canal slope, seepage discharge increases linearly. The hydraulic gradient and seepage velocity are minimum in the center line of canal. Increasing of hydraulic conductivity, causes to increase seepage discharge from canal body, linearly

Abstract In this study, the flow pattern and sediment transport amount in a meandering river reach located in the downstream of the Minab dam (Hormozgan province, Iran) were simulated using CCHE2D model. First, the topographic maps with appropriate scale of the study area were obtained by accurate surveying, then the model geometry and the numerical mesh network with different size were created. Second, the required parameters for running CCHE2D model were collected through field works. Finally, the model outputs, including flow depth and velocity and changes in suspended load and bed load sediment were obtained for the considered river reach. In the end, the two statistical criteria, including RMSE and MAPE were used to compare the parameters obtained from the numerical simulation model with the corresponding observed values. The RMSE of velocity, depth and energy slope were calculated equal to 0.075, 0.116 and 0.0008, respectively. The corresponding values of MAPE were obtained as 2.7, 6.2 and 4.4 percent, respectively. Comparison of the results confirmed the high accuracy and low error of the model in simulating the flow and sediment parameters.