IRANIAN WATER RESEARCH JOURNAL
Year:2020 | Volume:13 | Issue:4 (35) |Papers Count:20

Sand and gravel mining from the riverbed causes many environmental and social problems in the rivers because of disturbing the natural conditions of the bed and also, its changes. Some of these problems are subsidence of riverbeds and erosion of hydraulic structures its path, bank erosion and damage to land placed in riverbank, the destruction of dewatering openings, drainage of agricultural land placed in riverbank and also, the change of plant and animal environment. In studying the morphological changes of the rivers’ cross-sections, it is often assumed that the riverbanks are non-erodible or the erosion of river banks is less than the erosion of bed, so, river width is considered constant. A closer study of the changes in river alluvial, particularly, with the erodible banks shows that the river width will be faced with significant changes because of material mining. In this study, it has been tried to study the changes in the bed, bank erosion of the river and its causes and also to identify the vulnerable intervals by simulating hydraulic conditions of sediment flow in the Khorramabad River with the use of model Fluvial-12. The Khorramabad River is located in 36. 48 to 45. 47 East latitudes and 10. 33 to 50. 33 North longitudes and of the important branches of the Kashkan River. The case study includes an interval of the Khorramabad River with the length of about 7 kilometers before the inset of the Kakasharaf River. In this interval, the Khorramabad is a mature river in the plains with the average slope about 1. 6%, and a flow with u-shaped cross-section. In the mentioned interval, there a map with the scale of 1: 1000 that includes about 9 kilometers of the river and the hydraulic studies were performed on this interval. In the current study, 1372 cross-sections surveyed in 2003 were used. According to the changes in the sections along the way due to the construction of the bridge, the protection wall of the bank, river materials mining and encroachment the bed of the Moradabad River, firstly the required sections were extracted from the topographic map in the GIS environment using HECGeo-RAS interface. Then, these sections were modified in model HEC-RAS and inappropriate sections were removed. With this approach, totally, 51 cross-sections were entered in model HEC-RAS to introduce the geometry of the river in the studied interval. For hydraulic modelling of the sediments of the Khorramabad River in the studied interval, the model FLUVIAL-12 was used. This model was provided in 1972 by Cheng. A mathematical one-dimension model has been used to rout the flow and sediment in the natural and built waterways, but it cannot model the unsteady flow. In model FLUVIAL-12, digital techniques and physical relations are used to analyze the momentum, flow resistance and sediment transport. The main parameters required for calibration of the model, are roughness coefficient, sediment transport equation, coastal erosion factor, bed erosion factor and the factors such as these. Model FLUVIAL-12 has been tested with data from many different rivers in the world that most of the data was used to test and calibrate other models. Roughness coefficient of the Khorramabad River in the suited area was estimated by field survey, engineering judgment and completing the checklist of SCS method. To calculate the manning roughness coefficient, which is used in hydraulic model HEC-RAS, the values of vegetation, artificial irregularity and additional roughness of barriers created in the river by the people were considered in the calculation of river roughness coefficient. To calculate and estimate the manning roughness coefficient in floodplains and main section, US Soil Conservation Service (SCS) and also, field survey were used. The sediment transport was simulated by using the functions of the model, the Graph’ s (1970) sediment transport equation, Yang’ s (1972-1986) flow power unit, the equation of Engelund & Hansen (1976), the equation of Parker et al. (1982) for sand, the sediment equation of Akers and White, the equation of Meyer-peter & Muller for bed load (Shafaei Bejestan, 2005). Result revealed in the v-shaped sections and the channels with small sections, the bank erosion is developed after armoring the bed materials. Also, In the U-shaped sections and the channels with larger sections, the bed erosion is reduced and the development of bank erosion is inconsiderable after armoring the bed materials. Furthermore, in the sections that the shape and slope make the stable section, no significant difference will be observed in terms of erosion and sedimentation after armoring the bed materials. As it is mentioned before, importance of studying and discussing the river mining becomes clear. Each river has the sediment transport capacity depending on its discharge. There is a reverse relationship between the transport capacity and the size of the constituent grains, so that the coarse grains have the less transport capacity than the smaller grains. Therefore, determining the river transport capacity, the proper points to mine the materials according to the deposition intervals and the appropriate volumes of material mining according to the bed load requires the comprehensive studies on the potential of material mining in different parts of the country. Also due to illegal river mining activities in recent years, study on improving the rivers based on the modelling the current situation and providing the protection plans is essential.

Increasing global warming and decreasing rainfall are among the serious concerns in the world. Population growth and increasing demand of water for irrigation, household and industrial purposes are annually faced with water shortages during the summer months. Lakes and reservoirs are the greatest resource of fresh water. One of the more serious problems faced by industry is the evaporation of water from this type of open storages that allows great losses of water resources, particularly during the warm months. For example, in Sarcheshmeh tailing dam, the evaporation rate average is about 2250 mm per year, when this dam is filled with water to the depth of 5000 mm. In this condition, approximately 45% water might be lost due to the evaporation. Thus, employing techniques for reducing and controlling evaporation from open storages is necessary for conserving water. This issue has been investigated in some countries, in both theoretical aspects and practical applications. The most considered approach is the application of chemical evaporation reducing layers over the surfaces of large water bodies such as reservoirs, lake and the like. Such application is especially important in arid and semiarid areas. Among the surfactants tested, biodegradable fatty alcohols with low toxicity have presented the highest resistance to water evaporation. The current investigation has verified the influence of monomolecular films of fatty alcohols (including Hexadecanol and Octadecanol) in reducing the evaporation. For this purpose, two types of water samples were collected from drinking tap water and the reservoir of Sarcheshme tailing dam, during two months. For sampling the two source of water, twenty steel rectangular containers were provided, with dimensions of 15*30*5. Six of containers were filled with 500mli tap water and six other containers were filled with the water collected from Sarcheshme dam reservoirs. For each water samples, five containers were considered with monolayers film and a container of water with no monolayer was used as the control. Monomolecular films were used in ten containers, filled with two samples water. They were included pure hexadecanol (C16), pure octadecanol (C18) and mixtures of 1: 9, 3: 7 and 5: 5 (m: m) of C16 and C18 (C16: C18). The layers were applied on the surface of the samples by adding small volumes of ethanol solution (40gr/L) using a sprayer. Values of cumulative evaporation were collected during a 29-Day Period from 17/07/2016 to 14/08/2016. In all samples tested, the performance of fatty alcohol on drinking water and wastewater was different, at the same condition. It was observed that, in samples 1, for the container of drinking water which was covered with pure hexadecanol film, the evaporation reduction of 32. 2% was obtained. While for the container of wastewater, the same value was observed as 18. 2%. The results from testing the C16: C18(1: 9) mixture (samples 2) showed 39% saving water for drinking water and 32. 2% saving for wastewater. Mixtures of hexadecanol and octadecanol with weight ratios of 3: 7 (samples 3) showed the highest performance in reducing evaporation (58. 47%, 51. 75%) of drinking water and waste water, respectively. For the C16 and C18 mixtures (samples 4), the best results obtained from drinking water and wastewater (47. 5% and 45. 5%) were at 1 to 1 proportions (C16: C18 (5: 5)). The outcomes from testing pure octadecanol (samples 5) were poor. This monomolecular film achieved 27. 1% and 21% saving water in drinking water and wastewater, respectively. According to the mentioned outcomes in the above tests, the minimum of difference between evaporation rate of drinking water and wastewater was related the mixture of C16: C18 (1: 9). In presented experiments results, it was found that the water evaporation rate, for all of the tests were performed on wastewater using fatty alcohol, was higher than tests which were done on drinking water. It may be concluded that acidic condition and the organic and inorganic compounds in wastewater of Sarcheshmeh tailing dam, with the effectiveness of the monomolecular film led to increase the evaporation rate. It is noticed that in mixed films, the differences in rate of evaporation losses of both drinking water and the wastewater was reduced when the proportion of octadecanol to hexadecanol was increased. It is well known that octadecanol films can reduce water evaporation better than hexadecanol films, but C16: C18 mixed films was reduced evaporation rate more than the pure films.

Multi-criteria decision making (MCDM) and Geographic Information System (GIS) are using in natural sciences for accurate decision making and the evaluating parameters. Decision making in agriculture is influenced by different factors such as: production and irrigation system expenses, water availability and quality, soil characteristics, climate conditions, labor skills, and cultural acceptability. The present study was conducted over an area of approximately 11081 ha, in the Izeh plain Khuzestan province, south west of Iran, during 2015-2016. Results of the comparison (for each factors pair) were described in term of integer values from 1 (equal value) to 9 (extreme different), where the higher number means the chosen factor is considered more important, in a greater level than the other factors being compared with. Analytic Hierarchy Process (AHP) is one of Multi Criteria decision making method that was originally developed by Thomas L. Saaty (1980). In brief, it is a method to derive ratio scales from paired comparisons. The AHP has been used for optimizing. Spatial analysis to identify susceptible regions for pressurized irrigation systems starts with representing each selected physical sub-criterion by a thematic layer, in which each point takes a value (1 to 9). For this purpose, the samples have been gathered in a laboratory or qualified according to that criterion. In order to layer all the criteria, data were gathered from satellite images and official sources at different available forms (digital and hard copy maps, tables and charts). Then, they were analyzed and treated using GIS and geostatistical tools. Each layer was obtained in raster data model. Spatial data on water characteristics, topography and climate (temperature map) were obtained from Khuzestan Water and Power Authority, which is the Iranian official source of agricultural spatial database. Data were available in digital format with 1/150, 000 scale. Major advantage of AHP is to formalize and renders systematic that is largely a subjective decision making process and as a result facilitates ‘ accurate’ judgments, in which weights of criteria are also provided for decision maker, and sensitivity analysis is easy to conduct by using computer. The weights of each criterion were computed by using the geometric mean. After that, the weights were aggregated and each weight divides on aggregated weights, in order to be normalized. The normalized weights determine the priority of criteria. The sum of all normalized weights in each Table was equal to unity. The AHP methodology says that prioritizing and weighting the criterions should be done at first. According to fundamental Saaty's scale for the comparative judgments and by performing pair-wise comparisons of criteria with respect to the object, here the comparison and calculation of criteria were done in 1st, 2nd and 3rd levels to localize irrigation system as an example. Most large drip irrigation systems employ some type of filter to prevent clogging of the small emitter flow path by small waterborne particles. New technologies are now being offered that minimize clogging. Considering conditions of water used for irrigation in the study region, suspended materials (W sm) and biological materials (W bm) were seen in the water according to laboratory experiments. In the studied field, irrigating water was available by pumping from wells and filters were employed in the irrigation system, but filters need to be changed after a while, so possibility of clogging in the drippers still exists. Therefore, these two alternatives have higher weight than available water. The amount of Sodium concentration (W na) was low and has less importance than other criteria except available water. Localized irrigation systems designed for no leaching fraction. High electrical conductivity (EC) of soil and irrigation water may accumulate salts in the root zone, but EC of the study region was almost low. However, alkaline water (refers to pH) could make sediments in the drippers In this study surface irrigation system was identified as the best system for this region. The comparisons expose that the results from the proposed model are in good agreements with the results from field investigations. An additional benefit of the model is that the decision-maker can perform a more exhaustive conceptual comparison of the different decision components. As an extensive set of factors involved in selecting an irrigation system has been included in the proposed model, it can be claimed to be a comprehensive and practical model. Hence, it can be used in selecting the irrigation methods for various agricultural sites, thereby improving soil and water resources exploitation and productivity.

Occurring periods of drought in the past decade, increasing growth of population, and limiting surface water resources necessitate the proper management of the reservoirs of dams. Operation of reservoirs is influenced by a lot of goals which many of them are incompatible with each other. The inflows to the reservoir and the storage volumes are uncertain which increase complexity in the operation of the reservoir. The main challenge is to find the best situation of the reservoir release and optimize hydro systems. Various optimization methods have been introduced for the operation of the reservoir. But some of these methods have disadvantages that use of them is not possible in all conditions. Bozorg Haddad (2005) used Honey Bees Mating optimization for solving design problems and the Ant Colony algorithm was also used to exploit a four-reservoir system in a discrete space that was able to optimize the problem with greater accuracy and less computing time than the genetic algorithm (Jalali et al. 2007). Mousavi et al. (2017) used the Harmony Search Algorithm for the optimization of water powerhouse storage projects and reported satisfactory results. Harmony Search algorithm was presented by Geem et al. for the first time in 2000. In this research Harmony Search Algorithm (HSA) is evaluated to determine the optimal operation of multi-reservoir systems. Then in order to evaluate the ability of the algorithm to solve real problems, the optimal operation of Dez Dam reservoir in Khuzestan province, Iran, has been considered for the period of 10 years (1990-1992) with 120 months. In the single-reservoir of Dez Dam, the goal is to provide of agricultural demand of downstream or to determine the optimal monthly release for 10 years operation. The optimum value was obtained by using a linear programming model (Lingo). Lingo model can solve nonlinear problems and provides the global optimum in some cases such as the intended problem where the objective function is convex. Therefore, the solutions obtained from the HSA model were compared with the outcomes of Lingo software. A new heuristic algorithm derived from an artificial phenomenon found in musical performance, namely the process of searching for the better harmony, has been introduced. Music harmony is a combination of sounds considered pleasing from an aesthetic point of view. Harmony in nature is a special relationship between several sound waves that have different frequencies. Musical performances seek the best state (fantastic harmony) determined by aesthetic estimation, as the optimization algorithms seek the best state (global optimum-minimum cost or maximum benefit or efficiency) determined by objective function evaluation. Aesthetic estimation can be found by the set of the sounds played by joined instruments, just as objective function evaluation which is obtained by the set of the values produced by component variables. The sounds for better aesthetic estimation can be improved through several practices; just as the values for better objective function, evaluation can be improved by several iterations. The new algorithm is named Harmony Search (HS) and the steps in the procedure of HS are as follows: Step 1) Initialize a Harmony Memory (HM); Step 2) Improvise a new harmony from HM; Step 3) If the new harmony is better than the least harmony in HM, include the new harmony in HM, and exclude the minimum harmony from HM; Step 4) If stopping criteria are not satisfied, go to Step 2. Harmony Memory Considering Rate (HMCR ranges from 0 to 1. If a uniformly generated value between 0-1 occurs above the current value of the HMCR, then HS finds notes randomly within the possible playable range without considering HM. For improving solutions and escaping local optima, another option may be introduced. This option mimics the pitch adjustment of each instrument for tuning the ensemble. For computation, the pitch adjustment mechanism is devised as shifting to neighboring values within a range of possible values. A Pitch Adjusting Rate (PAR) of 0. 10 means that the algorithm chooses a neighboring value with 10% probability (an upper value with 5% or lower value with 5%. In the present study, first HSA was used for the optimization of a four-reservoir system. The objective function was calculated as308. 2915 and 308. 2900 using Lingo software and HSA, respectively, which had a different of 0. 0005 percent with the global optimum. After the success of HSA in solving the four-reservoir system, a ten-reservoir system was considered. This time, the objective function was calculated as1194. 4 and 1193. 1 by using Lingo software and HSA, respectively, which had a different of 0. 1 percent with the global optimum. In the single-reservoir problem of Dez Dam, the value of global optimum of the objective function was calculated as 1. 9188 and 1. 944 by using Lingo and HSA, respectively, which had the different of 1. 31% with the global optimum. So, it can be concluded that this algorithm has the ability to solve optimization problems of the real system.

The hydraulic jump is one of the important phenomena of water flow in channels that in proportion to the intensity of the jump, faces significant energy dissipation. True hydraulic jump forms for the Froude numbers greater than 4. 5. Position of steady jump is the least sensitive type to fluctuations in the tail water elevation and forms steadily at the same location. The change of flow state from supercritical to a subcritical state is accompanied by discontinuity in depth of flow, formation of a surface roller, visible air entrainment and two phase flow, significant turbulence, kinetic energy dissipation, generation of spray and sound. The basic characteristics of a hydraulic jump are defined such as conjugate depth, location of jump, the energy loss in the jump, efficiency of jump, the length of the jump. From the designer's standpoint, hydraulic jump is a powerful energy dissipation mechanism and due to its erosive potential, is the centroid of scour. In order to take full advantage of the hydraulic jump in apron design, the erosive effect of jump should be confined to the limits of the heavily protected bed surface, hence intensive scour energy would not cause any harm to apron. This is why; hydraulic jump should be in a stilling basin with a fixed location. Turbulent flow over a rough surface is an important problem and it has been subject of diverse fields. Using roughness elements at the bottom of the flow causes increase in resistance to the flow hence accelerate the upstream flow development and increase in amount of kinetic energy, converted into the turbulent energy. Using of rough beds is an effective factor in reducing costs on energy dissipation basins. So researchers’ next purpose has been the use of roughness beds in the stilling basins bed and investigation the effect it on hydraulic jump characteristics. In this research, experimental investigation was carried out on the effect of bed roughness on hydraulic jump characteristics. It was done in a flume with length of 12 meters, width of 0. 5 meters and height of 0. 7 meters, in the range of Froude numbers 5. 5 to 9. Also, 24 cubic rough beds was used with staggered and strip arrangement, different rows and angles. Discharge was measured by a triangular weir with a 90° angle, placed at the end of channel and size of cubic blocks was 0. 05 meters. Point gauges with a sensitivity of ± 0. 1 mm used to measure the depths of flow. To evaluate the effect of roughness, both staggered and strip arrangement were used in the experiments. For creating a hydraulic jump, a sharp sluice gate has been used in the condition which the rough beds in downstream places. Relative depth and relative length was obtained as a function of Froude number. The relative depth values on smooth beds obtained in the present study were in good agreement with the data of Belanger classic jump. Relative depth, relative length and shear force coefficient increase for staggered arrangement, strip arrangement and smooth bed with increasing Froude number. The results showed that in the same Froude number the values of relative depth and relative length in smooth bed is less than those values on rough beds whereas shear force coefficient on rough beds is greater than smooth bed. Equations were obtained with SPSS software for jump relative depth. Results indicated that relative depth and length for staggered arrangement, in compare with strip, have more reducing ratio in smooth bed. Also, they showed, staggered arrangement produced better performance compare with strip arrangement in the ratio of secondary to primary depth and the ratio of length to jump primary depth. Both types arrangement had a better performance compared with jumps formed on smooth beds. For staggered and strip arrangement, the average of length ratio to jump primary depth was obtained 1. 9 and 1. 6 times less than smooth bed, respectively. In the experiments, the ranges of relative for the staggered and strip arrangement were 20. 47 to 39. 04 and 46. 66 to 24. 28, respectively. Shear force coefficient, that is the main factor is in reducing of depth and jump length, calculated 6 percent more of smooth bed in both arrangements. Generally, the experimental results of the current study are matched with the other similar researches on different types of rough beds. Finally, the equation for estimate of relative depth and relative length for Froude numbers extracted. By the results, the effects of arrangements in the level of 5 percent were proofed for all beds on relative depth and relative length.

Increasing attention to environmental issues in management of rivers causes the development of research in the field of hydraulic parameters and sediment transport in the rivers. Vegetation in many rivers has a significant impact on the flow hydraulic, morphology and sediment transport processes. Understanding the hydraulics of flow in a compound channel with vegetated floodplains is very important for determining the stage-discharge curve and for supporting the management of fluvial processes. There are few models within CFD codes that conceptually or physically represent the hydrodynamic impact of a vegetation canopy on the velocity field and conveyance characteristics in estuarine or riverine systems. The present research investigates the numerical and experimental modelling aspects of flow in compound channels with vegetated floodplain, emphasis to the suspended sediment transport. This study has proposed a method for predicting the depth-averaged velocity in compound channels with vegetated floodplains, based on an analytical solution to the depth-integrated Reynolds-Averaged Navier-Stokes equation (RANS) with a term included to account the effects of vegetation. Two-dimensional advection-diffusion equation was used to calculate the dispersion coefficients and sedimentation rate. This equation was solved by using a finite volume method. The vegetation was modeled via an additional term in the momentum equation to account for the additional drag force. The method included the effects of bed friction, drag force, lateral turbulence and secondary flows, via the four coefficients of f, CD, λ & Γ , respectively. This model was able to estimate the velocity distribution in channels with different dimensions and different vegetation densities. The wake interference model given by Nepf (1999) is used to estimate the bulk drag coefficient. Modified forms of the Colebrook– White equation can be used to calculate local friction factors in compound channels with vegetated floodplains. Several eddy viscosity models have been used in the literature to predict transverse momentum exchange in the mixing layer. When velocity profile is obtained, the dispersion coefficient can be evaluated and the remarkable role of vegetation is revealed. Both the velocity profile and the dispersion coefficient have been validated using our new experimental results. The model was applied in inverse mode to estimate the model parameters that quantified eddy viscosity coefficient, secondary flow, longitudinal dispersion, transverse dispersion and filtration in the experiments. In addition, the Elder’ s and Neph’ s relationships also calibrated to calculate the longitudinal and transverse dispersion coefficients. Levenberg-Marquardt algorithm was used to find the values of the model parameters that minimized the sum-of-squared differences between measured and modeled velocities and particle concentrations. Experiments performed in a flume of the Hydraulic laboratory. The experimental channel employed in this investigation had 10 m long × 0. 3 m wide and 0. 6 m deep. The channel has a simple rectangular cross section; however, this was modified by using Plexiglas sheeting to produce an asymmetrical compound shape. The artificial stems were PVC rods of 5 mm outside diameter, arranged in staggered grid. The model substance used as suspended load was silica of mean particle diameter around 7µ m and density 2143 kg/m3. Silica suspensions were injected to produce fully mixed inflow concentrations of about 6 g/l. In general, two series of experiments have been done in this study. In the first series of experiments, the depth-averaged velocities were measured. The second series have been conducted to estimate the rates of sedimentation. The depth-averaged velocities were measured by using micro-propeller and pitot tubes. Results showed that useing constant coefficient of 0. 0683 for eddy viscosity coefficient had not a significant impact on depth averaged velocity. The error about 1% was observed comparing the results of numerical modeling and experimental data, when the relationships of 0. 417δ ρ gS0HDr and 0. 62δ ρ gS0HDr were used for the secondary flow coefficients to the main channel and floodplain, respectively. Results showed that dispersion coefficient in vegetated channels increased cross the main channel compared to no vegetated case, due to the gradient of velocity. Sedimentation rate coefficients were calibrated by comparing the experimental and numerical sedimentation rate. The numerical model underestimates the experimental data about 8%. Experimental data of Zong (2011) were used to verification of numerical model. The results showed that the modified model overestimates the data with 22% difference. Consecuently, the quasi 2D model reproduces a reasonable simulation of the flow field and sediment transport in compound channels with vegetated floodplains.

Urmia Lake basin is one of the main important cereal production areas of Iran. In recent years, climate change affected the elements of the hydrological cycle in the basin. Better management of available water requires good understanding of trends in water budget elements in the basin. In recent years, many studies conducted on trends in rainfall depths in Urmia Lake basin. However, less attempt were done on understanding the trends in the number of days (NOD) with rainfall (R) in this watershed. This study tries to fill this gap by classifying the rainfall depths into the five distinct classes and analyzing the trends in NOD with rainfall in Urmia Lake basin. Therefore, the aim of this study is to detect trends in the number of days with different rainfall depths (received in 24 hours) and in five distinct classes, in Urmia Lake basin. In order to detect trends, the information of the twenty five stations having at least 10 years consecutive daily rainfall data were used. Data of daily rainfall depths provided from IRIMO. In each year the number of days with rain in the five distinct classes counted for every site. Therefore, for each station the NOD with R in a certain class created. Trends of the mentioned time series detected using the non-parametric Mann-Kendall (MK1) method. We considered the significant autocorrelation coefficients in trend analysis. For this purpose the modified version of MK method by Hamed and Rao (1998) was used. Moreover, slopes of trend lines estimated using the Sen's estimator approach. In order to analyze the spatial trends for each of the time series, some relevant maps prepared in which the stations having significant trends were shown by markers. This could facilitate the interpretation of trends in the area under study. Results showed that the slope of trend lines for the NOD with R between 0. 1 and 1 mm is often positive. About 84% of the stations had upward trend line. The five stations located in the southern part of the basin experienced significant upward trend (in level of 10% or less) in the NOD with R between 0. 1 and 1 mm. The slope of trend lines for the case of the NOD with R between 1 and 5 mm were almost negative. In the case of days with rain between 1 and 5 mm, the 15 stations had downward trend lines, which five of them showed significant trend; whereas the remaining stations had upward trend line slopes (insignificant at 10% level). However, the slope of trend lines for the NOD with R between 5 to 10 mm in 44% of the stations were negative, in which only four of them were significant (in 10% level). Trend line slopes in 40% of the station were positive, in which only one station experienced significant trend at ten percent level. The steepest positive trend magnitude belonged to the station namely Herris, with β = 1. 633 (day/year). For the NOD with R between 10 and 15 mm, about 32% of the stations had negative trend line slopes. However, only three stations experienced negative significant trends. About 26% of stations had positive trend line, in which only one section (Maraghe) exhibited significant trend in 1% level. The steepest slope of the trend lines belonged to the station Shahindezh with β = 0. 585 (days/year). The slopes of trend lines for the NOD with R greater than 15 mm were positive for 52% of the stations. However, only one of them experienced significant trend (in 10% level). Moreover, 24% of the stations had negative trend in the mentioned class. Among the total of 25 selected stations only one section (Maraghe) had significant negative trend. The steepest slope of the trend lines belonged to the station Herris with β = 0. 464 (days/year). In general, trends of the NOD with R less or equal one mm in Urmia Lake basin were upward. But trends for the time series of the NOD with R in the classes of 1-5, 5-10 and 10-15 mm were downward. This means that light storms events in the study area are going to be occur frequently but heavy rains is going to be rare. It can be concluded that the number of light raining days in a year had increasing trend. This implies that such light rains can not to be utilized by crops and trees, because such rains immediately can be lost by evaporation process after ceasing the rain. However, heavy rains which showed increasing trends for most of the selected stations produce large floods in the rivers discharging Urmia Lake.

Sewage and wastewater are extensive sources of water in the suburbs of many cities. In many parts of the world, treated sewage and wastewater have been successfully used for irrigation, and many researchers have recognized its benefits. In arid and semi-arid regions, good conditions are provided for planting of susceptible species by irrigation with sewage or wastewater for development of green cover and economic exploitation such as wood production. The aim of this study was to plant different eucalyptus species irrigated with industrial and household sewage and wastewater. Eucalyptus has been considered because of high growth rate and resistance to biotic and non-biotic stresses as well as high product of wood. In this regard, the study was conducted by measurements of yield, water use efficiency and some performance indicators in three eucalyptus species that were planted in drainage lysimeters and irrigated with wastewater. The experiments were carried out in Yazd city and greenhouse condition. The research was conducted by factorial experiment in completely randomized design and three replications. Two main treatments were applied: Irrigation with wastewater in three levels (control or without wastewater, 50% water and 50% wastewater, 100% wastewater). The examined eucalyptus species were Eucalyptus microtheca, Eucalyptus camaldulensis and Eucalyptus rubida. Each treatment was applied to tow eucalyptus trees or two pots. Seedlings planted in drainage lysimeters (pots) with 7 liters capacity and they were kept for four months. The soil applied for the experimental pots was a field soil with loamy sand texture (76% sand, 20% silt and 4% clay). Wastewater was provided from the wastewater treatment plant of Yazd city. Wastewater samples were taken during the irrigation period. The chemical and biological analyses of the wastewater were according to standard methods. We studied the influence of irrigation with wastewater on high and diameter of trees, length and wide of leaves, leaf surface, dry mass of leaves, stem and root, specific leaf area, shoot and root dry mass, chlorophyll content and water use efficiency (WUE). The significance of differences between mean values was determined by one-way analysis of variance. Duncan’ s multiple-range test was used to compare the means. The use of tree plantations for the renovation of wastewater and the simultaneous production of forest produce is now being widely studied. In the condition of wastewater use, the presence of nutrients and organic matter in the wastewater helps develop growth and water use efficiency in some plant species. However, applying sewage or wastewater creates undesirable effects in soil, such as direct effects on soil suitability for cultivation and water availability. The use of wastewater for irrigation of fast growing trees can be useful. Wastewater can bring excessive fertility elements into the soil. Therefore, irrigation with wastewater can cause increase in number of leaves, length and width of leaves in plants. Increase of leaves number and leaves area can improve the absorption of solar energy and enhance the efficiency of photosynthesis. Irrigation with wastewater can accelerate the flowering of plants and make the produced seeds healthier. All of these factors can improve water use efficiency in plant. The results of the study showed the potential for utilizing tree plantations with wastewater management. According to this study, there was a significant difference between irrigation treatments at 1% level (p <0. 001) on morphological characters such as height and diameter of trees, length, width and leaf area. Specific leaf area, leaf water content, chlorophyll content also increased with increasing of wastewater concentration. We observed significant different at 1% level (p <0. 001) between of different irrigation treatments. In 100% treatment wastewater, chlorophyll content increased up to three times than the control treatment. Shoot dry weight and water use efficiency were improved with increasing of wastewater concentration which can be due to the high levels of fertilizer elements in the wastewater. According to the results, there was significant difference between trees species in the number of morphological and physiological characteristics. By increasing the amount of wastewater concentration, these characteristics improved in three species experimented. E. camaldulensis had the highest growth and water use efficiency than others; therefore it can be appropriate for wastewater irrigating conditions. We suggested that for economic use of wastewater for wood producing, E. camaldulensis is more suitable than other species in this experiment.

Vast part of Iran, including Chaharmahal and Bakhtiari province, is categorized as arid and semi-arid. Thus, in the most parts of the region, groundwater is the only water resource, and is the major constraint on economic and social development. In arid regions, the underground dam is a new industrial site of supplying water for farming, especially in summer. An underground dam is a sub-surface barrier across the stream which retards the natural groundwater flow and stores water below ground surface to supply the demands during the period of need. The aim of this study was to prioritize the effective factors in the construction of underground dams and to develop and evaluate a multi-criteria decision making system, based on GIS techniques, to identify and prioritize potential areas for building underground dams in the watershed of Shahrekord. Marghmalek-Shahrekord watershed is in the north-east of Chaharmahal and Bakhtiari province, Iran. This watershed is located in Sanandaj-Sirjan zone based on structural divisions. The atmospheric rainfall in the basin is mainly influenced by low-pressure Mediterranean systems. In order to accelerate the decision-making process, as well as avoiding the accumulation of excessive information for a surveyed problem, it is necessary to eliminate inappropriate points by considering a number of key criteria and factors. At the first, appropriate areas for establishing underground dams were determined with omissive criteria and using Boolean logic. The axes which do not cut the Qanat's gallery and are suitable from the aspect of length and area of the reservoir were identified. In the next stage, the proposed locations were prioritized using the analytic hierarchy process. Therefore, the indices that are more fit match the more suitable axes for the construction of underground dams in the study area. Five scenarios were considered for the prioritization. Quaternary formations are appropriate for the construction of underground dam. Poor, medium and good rangelands and garden lands are also suitable for underground dams. According to the first, second, third and fourth scenarios, the axis number 46 and according to the five scenarios the axis number 41 have the first priority for groundwater dam construction. The results showed that the hydrologic and the socioeconomic factors were chosen as the most important factors with weights of 0. 51 and 0. 30, respectively. In determining the value of the indicators, the water quantity (runoff height) with a weight of 0. 833 and also the depth of alluvium with a weight of 0. 743 are more important than other indicators, which indicates the importance of the hydrologic criterion for experts. The best axes for the construction of an underground dam are in the alluvial river bed with high subsurface flow, the large reservoir capacity, high runoff volume and areas with high permeability and low slope. By integrating the maps of the Qanats axis of the study area and the map of possible gaps of underground dam construction, 15 axes were identified for the construction of underground dam in Marghmalek-Shahrekord watershed. The results of the reservoir analysis indicated that suitable subsurface reservoirs in these areas are matched with this fact that with decreasing slope, the length of the reservoir increase, that ultimately causes increases the volume of the reservoir. The large area of the watershed upstream of the dam has a higher priority and value because the high amount of runoff passes through the construction site. The depth of the alluvium has the most relative importance among the axis indices, because the length and depth of axis are most important in the economy of an underground dam. By investigating the results of the reservoir depth, it was found that the best region are alluvial bed with the depth of less than 10 meters, that is consistent with the researches of Chezgi (2015). The water of these levels is very good in terms of quality because they are naturally refined by constituent lands. Also, they have a high subsurface discharge. These valleys are the best and most appropriate places for underground water extraction. According to the obtained results about the slope, the relative importance of the slope increases with its lowering. This study showed that most of waterways 3 and 4 were located at slopes of less than 5 percent, which are suitable areas for building underground dam. The reason is that the gradient factor has inverse relationship with reservoir volume and permeability, which is consistent with the results of Nilsson (1988); Rezaei et al. (2013) and Chezgi (2015). The proposed method can accurately be used to select the suitable sites for construction of underground dams through detailed and accurate surveys and by considering the effective factors.

Shallow water table is an important problem in arid and semi-arid regions. Since it causes reduction of agricultural yield; therefore, water table fluctuation is necessary to be monitored in irrigation and drainage fields. These conditions are intensified for arid and semi-arid countries, such as Iran, where saline groundwater is the main water resource. These problems were increased in sugarcane industrial farm that covered large area in Khuzistan province, Iran. Therefore, it is necessary to determine water table in sugarcane field during growing season. Regarding the purpose, it is important to evaluate water table fluctuations in each farm continuously. There are some problems to achieve this purpose like spending time and financial supports. So, computer models are developed to solve the problems. In the other hand, water table can be simulated under different farm conditions, even before designing an agricultural unit, using the models. In order to achieve the mentioned goal, this research was conducted to evaluate three models: DRAINMOD, SWAP and Endrain, to simulate water table levels in Amirkabir Agro-industry farms. The studied area is located at latitude between 31˚ 15’ and 31˚ 40’ and longitude between 48˚ 12’ and 48˚ 30’ , southwest of Iran. Regarding this aim, water table data were collected from a 25 ha farm. Each model use different equations to simulate water table. Nevertheless, Richards’ s equation is the main formula to determine water movement in saturated and unsaturated soils. SWAP uses this formula as following: Where: θ is volume of water content (cm3. cm-3); t, time (hr); z, increasing in depth to soil surface (cm); K(θ ), hydraulic conductivity (cm. h-1) and h is hydraulic pressure (cm). In order to estimate all of those parameters, sample data were collected from the farm. In addition, RETC model was used to determine some of mentioned data. Upper boundary conditions like irrigation and rainfall were measured from local sensors. For simulating evapotranspiration, meteorological data were collected from the nearest metrological station. SWAP uses FAO Penman Monteith equation and Drainmod applies Thornthwaite formula. Lower boundary conditions were also determined based on soil and drains conditions. Before simulation, all data were randomly sorted out. Then, 70% of them were used to calibrate those models and the 30% of remained data were used for validation. Four statistics criteria root mean square error (RMSE), modeling efficiency (EF), coefficient of residual mass (CRM) and coefficient of determination (R2) were used for evaluating the results. The calibration results of soil physics parameters for SWAP and DRAINMOD revealed that in both models, the parameters n and Alpha had the most variations compared with the other parameters. Similar results were cited by other researchers. In calibration stage, the amount of R2 for DRAINMOD model was 87. This result showed that there was a good correlation between field and simulated data. The result of R2 for SWAP and ENDRAIN models were 83 and 93, respectively. RMSE values for DRAINMOD, SWAP and ENDRAIN were 12. 42, 10. 46 and 11. 63 cm, respectively. So, in the calibration stage, SWAP had more accuracy, compared with the other models, to determine water table. The CRM values were obtained as-0. 028,-0. 022 and-0. 061 cm for DRAIMOD, SWAP and ENDRAIN, respectively. Then, all three models lead to overestimate of water table. The results of EF were 0. 83, 0. 85 and 0. 88 for mentioned models, respectively. Validation results of DRAINMOD model revealed that RMSE, CRM and R2 were 13. 19 (cm),-0. 008 and 0. 85, respectively. These statistical criteria were found to be 17. 00 (cm), 0. 020 and 0. 82 for SWAP. These parameters were obtained as 28. 10 (cm), 0. 603 and 0. 82 for ENDRAIN model. Therefore, all the models had acceptable error to estimate water table depth. The results of EF were 0. 84, 0. 75 and-2. 80 for DRAINMOD, SWAP and ENDRAIN models, respectively. These results showed that ENDRAIN was inefficient to determine water table. It is due to lack of using parameters to simulate all boundary conditions in soil. However, since DRAINMOD simulates evapotranspiration and downside boundary conditions well, the mentioned results were better rather than two other models. Although DRAINMOD had a better accuracy compared with SWAP, both of those models had good efficiency to simulate water table. Thus, DRAINMOD had overestimate error and SWAP and ENDRAIN had underestimate error. DRAINMOD is recommended as a better model according to the higher coefficient of determination and lower error value.

In this paper, the effect of suspended sediments on the bed shear stress distribution and hydraulic jump characteristics in a symmetrical trapezoidal channel with 45° side slope is simulated numerically. Observations showed that for lowers sediment concentrations (namely below 8%) both the hydraulic jump and the bed stress distribution became asymmetric, while for the higher sediment concentrations, the flow features were symmetric. It was also observed that the bed shear stress and relative energy losses increased with the sediment concentration, but the jump length decreased. The results indicated that for the inflow Froude number Fr1=7, by increasing the sediment concentration, the ratio of the hydraulic jump length to initial depth decreased by 18. 1% and sequent depths ratio increased by 17. 2%. Meanwhile, the relative energy loss was increased by 3. 2%. While the hydraulic jump phenomenon has been widely studied by various researchers on open channels, most of the experiments that are presented to calculate the hydraulic jump characteristics have been mainly related to rectangular channels (classic hydraulic jumps) by now. There are very few studies on the trapezoidal channels, although most of the water transfer channels are in trapezoidal shape. Accordingly, in the present study, the effect of trapezoidal channel side slope on shear stress distribution and jump characteristics (including energy deformation, jump length, and conjugate depths) will be investigated by using Flow3D numerical model. So, at first, model has been calibrated by using an experimental results published for trapezoidal channel of 45 degree side slope. The RGN model was selected from the turbulent models. Then, the model for different hydraulic conditions (Froude number 1. 5 to 12) and two slopes of 60 and 75 degrees has been performed and the results have been obtained. Due to the shear stress importance, which is usually not investigated in experimental researches, in this study the distribution of bed shear stress has been calculated in all three channels side slopes, and also the hydraulic jump characteristics. Generally, for computational fluid dynamics simulating, first it needs to evaluate and calibrate the numerical model with experimental results, then cite it after validating and ensuring its acceptable adaptation with the experimental results. In order to validate the model, the experimental research done by Omid et al. (2007) was used. Omid et al. experiments was done in a horizontal channel with glass sides and smooth bed, rectangular cross section with 0. 50 m wide and 9m long, side walls with three different slopes of 30, 45 and 60 degrees, divergence angle of 3 to 9 degrees and Froude numbers from 3 to 9. 8. With comparison of hydraulic jump length profile in different slide slopes, it can be said that the length and depth of the jump on different slopes have completely different behavior, so that by increasing the side slope, the jump length will decrease and the depth of jump will increase. Investigating the relative energy loss graphs on different side slopes of the trapezoidal channel and comparing it with the USBR results for the rectangular channels shows that in channel of 45-degree side slope with Froude number 7. 9 the maximum amount of energy loss occurs, in comparison to the side slopes of 60 and 75 degrees. In this study, by constant considering of the flume specification, the effect of cross-sectional shape on the shear stress distribution in the channel has been investigated. Concentration of shear stress on the left of channel of 45 degree side wall after hydraulic jump is noticeable, while such a situation is not observed in channels of 60 and 75 degrees side slope which their cross-sections are closer to the rectangular channel. This is due to the presence of a separation area on the bed called bottom rollers. In general, after hydraulic jump for Froude number greater than 3, by increasing the side slope, the amount of dimensionless shear stress is reduced. Comparison of channels with different side slopes indicates that the shear stress amount decreased after hydraulic jump, which the maximum amount by 48% loss will occur in channel of 45-degree side slope. According to this study, in comparison to trapezoidal channels with different side slopes, the hydraulic jump has a different behavior in channel of 45 degrees side slope. Compared to the well-known hydraulic jump in prismatic rectangular channels (classical jump), the flow configuration of jumps in trapezoidal channels is quite different. Classical jumps are characterized by a high velocity bottom jet and an overlying surface roller. Such jumps are usually referred to as two-dimensional. In trapezoidal channels, inflow is lifted in the air and forms a splashing zone because of the presence of a bottom separation zone, referred to as the bottom roller. Thus, the main stream flows near the surface and slowly diverges to the side walls. This is due to the concentration of the inflow to the center portion of the cross-section, and the resulting depression along the side walls. These are the characteristics of the trapezoidal channels. It is seen that the jump is asymmetric to the left; such asymmetries seem to be typical for relatively Froude numbers greater than 3. The results show that the maximum energy loss associated with the channel of 45 degree side slope and Froude number of 7. 9 by 84. 3%, which shows about 5% and 12% increase in efficiency relative to the channels 60 and 75 degrees, respectively. Comparison of the length of the jump to the initial depth indicates that the highest value is related to the angle of 45 degrees and shows a difference of 20% and 31% relative to the channel 60 and 75 degrees, respectively. Comparison of the graphs shows that with the increase of the side slope, from 45 degrees (slope 1: 1) to 60 degrees (1: 0. 58) and 75 degrees (1: 0. 27), the ratio of the sequent depths decreases.

Alluvial aquifers are one of the main and significant sources of water for agriculture, drinking and industry. Researches have indicated that climate change has a negative effect on charging the aquifers in some aired and semiarid regions, in recent years. Furthermore, groundwater overexploitation of many aquifers has led to withdrawal groundwater, dry out wells, subside the ground and damage facilities. The similar situation is occurring in Kuhpayeh Segzi and southern Mahyar aquifers, located around Gavkhouni wetland, Isfahan province, Iran, as well as increase in the extent of the salt marshes in the area. Therefore due to the importance of groundwater resources in the mentioned area, the water table changes and the storage of water reservoirs of these aquifers were investigated in this study, from 1981-1982 to 2012-2013. The studied area is located in west of Ghavkhouni wetland, Isfahan, Iran. The Kuhpayeh Segzi and Mahyar aquifer has the area of 417. 7 and 850 km2, respectively. In the current study, the average values of aquifers’ water table were calculated using the Thiessen method. The mean values of the water table obtained from the Kuhpayeh Segzi and southern Mahyar aquifers were recorded as the average level of water table in Gavkhouni wetland for the studied period. Then, the water table changes and the water storage of Kuhpayeh Segzi and southern Mahyar aquifers, as well as the average values of the above mentioned parameters were calculated for the study region. The change trend of water table was examined using the Mann-Kendall method which has been widely used to analyze the hydro-meteorological time series trends. Finally, a water table map was prepared in order to determine the direction of groundwater flow in the Kuhpayeh Segzi and southern Mahyar aquifers. However, due to the lack of piezometer wells in the Gavkhouni aquifer, field observations were conducted to analyze the groundwater flow and the interaction of the wetland and its leading aquifers. The results of this study showed that the average annual water table withdrawal in the Kuhpayeh Segzi aquifer was 0. 12 m which is amounted to 2. 75 m up to the end of the examined period. The storage of water reservoirs in the Kuhpayeh Segzi aquifer has decreased averagely by 7. 3 million m3 per year, with the total loss about 160 million m3. Whereas, the drop level of the water table in the southern Mahyar aquifer was 12. 83 m with the average groundwater table drop of 0. 57 m/year. The storage of water resources in the southern Mahyar aquifer averaged 13. 6 m3 per year with a total drop of about 300 million m3. The results of the study on the average changes of water table and the storage of water resources in the wetland area indicated that the water table drop and the depletion in the water resources in the Gavkhouni wetland area were 7. 8 m and 229 million m3, respectively, over 22 years. The results of Mann-Kendall test also showed a significant decrease in the values of water table in the studied aquifers during the mentioned period. The preliminary study on the water table maps of Kuhpayeh Segzi and Southern Mahyar aquifers revealed that the groundwater flows from these aquifers to Gavkhouni wetland. However, field studies determined that the water table of the Gavkhouni aquifer is higher than that of the Kuhpayeh Segzi and Southern Mahyar aquifers. In other words, the groundwater flow direction is from the Gavkhouni aquifer to the Kuhpayeh Segzi and Southern Mahyar aquifers suggesting that the Gavkhouni wetland has a nutritional role for the aquifers surrounding. In fact, it can be argued that due to the sever drop in the water table around Gavkhouni wetland at the last years of the investigated period, the hydraulic slope has increased and resulted in accelerated water depletion and increased of dry land extent in this valuable wetland. This means that surface drains have penetrated more quickly on the ground as soon as they enter the Gavkhouni wetland, and thus, less moisture remains within the wetland resulting in increased the salt marshes and dry lands. Consequently, to avoid the negative socio-economic and environmental effects, monitoring and managing the pumping of groundwater by authorized and unauthorized wells within the aquafers and nearby areas, as well as the periodic fluctuations of the Zayanderoud River is suggested.

Water consumption has been rising during the last five decades across the globe because of population growth, higher standard of living, and economic development. Water resources limitation in arid and semi-arid regions, such as the most parts of Iran, has led to the emergence of sustainable water resource management. To deal with the complex and interlinked water challenges, we need knowledge about the quantity and quality of water in the watersheds through water balance investigation. Evaluating available water resources is a prerequisite step in the water resources management to avoid adverse environmental impacts. In this regard, water balance investigations, as a tool for quantitative evaluation of water resources, is a crucial issue in water resources management and water policy making process. Water balance can reveal the differences in income an outcome flow of the watershed and changes by the source of nature and human activities. However in the current study, we have faced some problems to calculate water balance such as: it is costly and time-consuming to provide reliable data for a large area and moreover the estimation methods of water balance components rely on the methods that would not be appropriate for Iran's meteorological, hydrological and hydrogeological conditions. For example, in many cases, the empirical methods and mathematical models used in water balance studies in watersheds of Iran were developed in other countries with different climates. Water balance models have been developed over multiple timescales (hourly, daily, monthly and yearly) and different spatial resolutions and varying degrees of complexity. Water balance models were fi rst developed in the 1940s by Thornthwaite. With the increasing use of water balance models to address hydrological problems, a considerable amount of efforts has been devoted to the development of such models and techniques. A variety of models have been considered, ranging from relatively complex conceptual models to complex physical based models. Previous studies showed that using conceptual water balance models rather than process-based models or data-driven models have some advantages. Process-based models require high resolution, in both space and time, data and data-driven models may not remain valid in changed climatic conditions. Therefore, we focused on distributed and semi-distributed mathematical conceptual models. After evaluation different models, we introduced and classify some models that have relative advantages for being applied in Iran. As the primary criteria to choose, these models have at least one of the following properties: they are conceptual models, developed for water balance (not the other purposes such as flood simulation), suitable for different regions; they have been used for arid and semi-arid areas; they use a simple method for water balance calculation; and their code, software or graphical interface are available freely. To choose and modify an appropriate water balance model for Iran's watersheds, we should consider the simpler one. This chose is regarding to the fact that as well as the lack of data, there are usually uncertainties about the model parameters and input data. The uncertainty could be due to sparse data and lack of knowledge about the natural systems. In the current study varied types of models from hydrological simulation and fully distributed physical models to the distributed and semi-distributed conceptual models were investigated. Among them, we considered the models that have a fewer number of parameters for calibration and consider hydrological spatial variability in basins. Due to the advantages and disadvantages of these models, ability of applying in the watersheds of Iran was also considered. Regarding to these facts, it seems the model developed by Portoghese et al. (2005) could be a good choice for the most arid and semi-arid regions in Iran, after necessary corrections and modifications. This model, regarding all hydrological processes, avoids unnecessary complexities. The model of Portoghese was successfully modified and coded in MATLAB software and implemented in different watersheds of Razavi Khorasan province, by the name of QDWB (Quasi Distributed Water Balance model). The developed model was named Qusi-Distributed according to fact that it does not use cell-to-cell flow routing. The model results, such as runoff, actual evapotranspiration, and deep percolation were in agreement with other studies, and consistent with the basin hydrological process. This modified model has been assessed in six plains of Razavi Khorasan province, during a research project.

Alluvial rivers always change their hydraulic geometry to achieve a balance between water discharge, input and output sediment. Hydraulic geometry focuses specifically on the evolution of the river form and how the bed and channel influence this evolution. The morphology of alluvial rivers has led to the creation of two concepts: (1) at-a-station hydraulic geometry and (2) downstream hydraulic geometry (Julien, 2015). Downstream hydraulic geometry is defined by the top channel width (W), average flow depth (h), mean flow velocity (V), and slope of the flow energy (S) under bankfull conditions. Downstream hydraulic geometry as a function of hydraulic parameters and bed conditions, including flow rate, median size of bed particles and the Shields parameter is paramount to determine the state of a river. Therefore, various relationships have been derived based on various methods to estimate the channel hydraulic geometry, include: empirical relationships based on collected fields observation, and theoretical relationships based on governing equations such as flow rate, resistance to flow, secondary flow and sediment transport in alluvial river. Result of theoretical derivations indicated reasonable agreement with field observations and regime equations. In recent years, intelligent data driven methods has been used as new methods for predicting and estimating the parameters of complex hydraulic models. One of the common methods is the Group Method of Data Handling (GMDH) with self-organization approach, which has the ability to solve complex non-linear problems with higher accuracy and simpler structure. In GMDH method the coefficients of the polynomial are found by a Least Square Estimation (LSE) method. It is possible to combine the GMDH methods and optimization algorithms, by which a hybrid method will be created. In this method an optimization algorithm used to calibrate the weights of each neuron in GMDH rather than LSE method and so the hybrid methods may have better performance. The GMDH method is combined with artificial intelligence and optimization techniques such as harmony search (HS) optimization method. Harmony search algorithm (HS) is helpful to solve nonlinear problems, which was introduced in 2001 by Geem et al. based on a metaheuristic technique. The advantages of this algorithm are the fewer computations to find a solution, fast convergence and significant ability to achieve the optimal solution due to the appropriate structure. HS algorithm has become one of the most useful optimization algorithms because can be applied for both continuous and discrete problems. Since the GMDH algorithm has a self-organizing approach and its structure is initially unclear, the Harmony search algorithm is used to train and optimize the weights in the structure of each neuron in the GMDH network. In fact, the objective of HS submodel is to determine the optimal weights in short time to achieve the optimal GMDH structure and minimize the cumulative error between the measured and computed data sets. In this study, to predict and improve the accuracy of the relations of the downstream hydraulic geometry in alluvial channels, the GMDH model and a hybrid intelligent model based on the combination of GMDH and HS optimization algorithm (GMDH-HS) developed in the MATLAB software. Before using the developed models to predict and improve the accuracy of downstream hydraulic geometry in alluvial channels, it is necessary to check the accuracy of their results. Typically, researchers use the Mackey and Glass standard time series to verify the accuracy of developed models. Therefore, the validation of the developed models was done using the Mackey-Glass time series and calculated the verification results of the models for the two prediction methods, by the CE, RMSE, MSRE, MPAE and RB criteria. To evaluate the developed models, 880 data series were collected from previous research. This data set includes a wide range of field and laboratory measurement data. From this collection, 498 series were used to train and 382 remaining data series employed to test the models. The results of GMDH and GMDH-HS were compared with observed data. Also, the intelligent models results were compared with theoretical equations proposed by Lee and Julian (2006). Evaluating the performance of developed models, using statistical indices (CE, MSRE, MAPE, RMSE, RB and R2), indicates satisfactory performance of both models in predicting the downstream hydraulic geometry of alluvial channels. A closer examination and comparison of the results of the two models showed that the hybrid GMDH-HS model had a much better performance in predicting the hydraulic geometry. Also, the comparison of the statistical indices obtained from the results of both developed models with the theoretical relationships presented by Lee and Julein (2006) suggested the satisfactory performance of the hybrid intelligent model GMDH-HS in predicting the downstream hydraulic geometry in alluvial channels.

Heavy metals are hazardous pollutants that are usually produced by industrial wastewater and enter the aqueous environment. Their consumption by humans can cause health problems and even poisoning. The different kind of heavy metals such as lead is known as an important component in industrial wastewater. Environment pollution by heavy metals has affected human health and living organisms by a serious problem. Destructive effects of heavy metal can cause severe physiological or neurological damage to the human body. Therefore, heavy metals should be prevented to reach the natural environment. Today, the adsorption of heavy metals by natural adsorbents has been considered due to economic efficiency. Agriculture wastes or by-products have been investigated extensively for the removal of heavy metals due to their abundance in the nature. In recent years, natural materials have been used as adsorbent with low cost such as rice husk, mud, agricultural wastes, silica, ash, and solid wastes. Recently, attention has been focused on the utilization of unmodified or modified rice husk as a sorbent for the removal of pollutants. So far, few studies have been conducted on the simultaneous use of rice husk and active carbon to remove lead ions. Therefore, in this study, the adsorption behavior of rice husk, as a natural adsorbent, and activated carbon to remove lead ions was considered with the following objectives: 1-Evaluation of the absorption capacity of lead metal in aqueous solution by two adsorbent (rice husk and activated carbon). 2-Evaluation of Langmuir and Freundlich adsorption isotherm models, as one of the important factors in the design of adsorption systems to determining the adsorbent capacity and optimizing. This study is performed in three different doses of adsorbent the rice husk, and its silica (0. 5, 0. 75, and 1 gr/lit), initial concentrations of Pb metal (10, 15, 20, 25, 30, 35, 40, 45 and 50 mg/lit) on the uptake level, three different pH (4, 6, and 8), and in four contact times (15, 30, 60, and 120 min). Rice husk was obtained from rice mill. The rice husk was washed several times with distilled water and ethanol to remove pollutions. Subsequently, it was dried in the oven at the temperature of 90° for 3 hours. The rice husk was milled by a simple mill and separated by a mesh-size sifter 30 and 40, with the sizes between 425 and 600 μ m. The average diameter of particles reached about 510 µ m that were selected for testing. The activated carbon of rice husk silica was provided by heat a portion of the rice husk at 400 ° C for 4h. Metal salt Pb(NO3)2 was used to prepare the salt soluble with various concentrations of 1000 ml/ml of Pb ion in the stock solution. The separate experiments were performed in three distinct phases and then the remaining concentrations measured. 250 ml of three weight levels were used from two separate adsorbents of rice husk and activated carbon. In all experiments, the combination of solution and adsorbent were shaken on a shaker with the speed of 180 rpm. The mixture was separated of aqueous solution and rice husk from each other by the use of filter paper of Whatman No. 42. Then, that was analyzed by the Perkin Elmer atomic adsorption machine, model 2380, and with the flame method. The concentration was measured of metal in the effluent. The temperature considered for the test to be at 25± 1 ° C. All of the data have confirmed through both Langmuir and Freundlich isotherms. In this study, results showed that the removal efficiency of Pb2+ by rice husk and activated carbon from aqueous solutions are affected by pH, contact time, Pb2+ initial concentration and the adsorbent dosage. Investigating the time of equilibrium at different concentrations showed that by decreasing the initial concentration of the solution, the equilibrium time for both adsorbents (activated carbon and rice husk) decreased and its value was 30 minutes. The adsorption efficiency at different concentrations showed that by decreasing the initial concentration of the solution, the adsorption efficiency increased for both adsorbents. Activated carbon showed a higher ability to remove lead from the aqueous environment. The optimum pH and adsorbent dosage for Pb2+ removal was 6 and 1 gr/lit, respectively. It seems that with the increase in adsorbent dose, the specific surface area increases and thus the adsorption occurs more easily. The increase in removal efficiency of Pb with carbon dose probably resulted from the increase of total surface area and activated functional groups on carbons. The adsorption parameters were determined using both Langmuir and Freundlich isotherms. The results obtained from experimental data had a good conformity with the Langmuir equation output, but was better fitted to the results of Freundlich equation.

Among the different methods of removing nitrate from water, the adsorption process is the most appropriate way for purification and improvement of the quality of irrigation water contaminated with nitrate, due to of the easy implementation, design simplicity and economic considerations. In addition to economic losses caused by further utilization of nitrate fertilizers, nitrate leaching from agricultural lands imposes irreparable damages to the environment. Moreover, an important concern that the farmers deal with is how to manage the huge plant residues produced in the country. Therefore, converting low-cost agricultural residues into valuable organic reformed by the use of low-cost methods has attracted a significant attention. According to the above mentioned, the importance of finding suitable methods for the decrease of nitrate leaching from the soil and removing nitrate from contaminated water becomes obvious. To meet this purpose, the present study was carried out to investigate the effect of using Biochar layer on the absorption of nitrate from groundwater, as well as the effect of changes of dispersivity coefficient and absorption isotherm coefficient on the nitrate break through curve (BTC) and nitrate distribution profile. This study was conducted using two main treatments including soil bed without Biochar (control) and soil bed with a Biochar sandwich layer of 11 cm thick, by the use of HYDRUS-1D software. Sub-treatments were also consisted of three levels of dispersivity coefficient (0, + 50%,-50%) and three levels of Biochar absorption isotherm coefficient (0, +50%,-50%). Considering the increase and decrease changes of Biochar dispersivity coefficient and absorption isotherm coefficient, the simulated concentration values at different times and depths as well as the BTC changes at the specific points of observation and changes in the nitrate distribution profile were additionally studied. By transferring the model output to Excel and converting the time values to the pore volume, the BTC changes at different observation points and changes in the nitrate distribution profile were finally compared. The comparison of the different levels of dispersivity coefficient in layered soil and non-Biochar soil showed that the layered soil with a Biochar layer decreases the BTC peak and causes the BTC moves to the right side, which means the later and less exhaust of solutes from the soil bed. In addition, the nitrate distribution changes in the depths of the soil indicate the ability of Biochar layer for absorption of nitrate. The comparison of control treatment with all levels of dispersivity coefficient showed that the Biochar layer with contaminated absorption has significantly reduced the output contaminated concentration at all observation points. Furthermore the nitrate BTC in all depths moves to the right side and the output pollutant mass in each point is reduced with respect to the previous point. The comparison of changes in the-50% and +50% levels of adsorption isotherm coefficients with non-Biochar soil showed that increasing the value of adsorption isotherm coefficients causes the nitrate BTC moves further to the right side and also the rate of output nitrate concentration decreases compared with the control treatment. The existence of Biochar layer increases the transfer and distribution times of pollutants to the depths of the soil. The results in this study revealed that increasing the value of Biochar adsorption isotherm decreases the output nitrate concentration and causes the nitrate BTC moves to the right side (Retardation). The results also showed that the increase of the Biochar dispersivity coefficient decreases the reduction rate of output nitrate concentration and causes nitrate BTC moves to the left side. A comparison of the zero level of treatment with Biochar and the control treatment (non-Biochar) indicated the trapping of pollutants in the Biochar-soil environment and the reducing of the output contaminants in all observation points. Additionally by the results, the presence of the Biochar layer can decrease the content of nitrate distributed at the end of the column by about 61%. Furthermore, the transfer velocity of pollutants into the soil depth decreased with the increase of the Biochar absorption and decrease of dispersivity coefficient, which means the later and less exit of solutes from the soil column when the Biochar layer is used. The results of momentum analysis showed that the value of output pollutant mass from the column in the case of non-Biochar is 15. 36 (mg/cm3×h); While, in the case of using Biochar is 13. 78 (mg/cm3×h), which indicates a 10. 3% reduction of output pollutant from the column. In all treatments, this reduction was lower than that for the control treatment, meaning that Biochar can absorb contaminants (in all conditions) from the aquatic environment and reduce the contaminant percolation to the soil depths.