نشریه دانش آب و خاک
سال بیست و هفتم شماره 3 (پاییز 1396)

Runoff coefficient can be used as a measure for assessing the flood generation potential of the watersheds. This factor is depending on the watershed characteristics and may vary temporally during a year. Knowledge on the watersheds with higher potential to runoff production and determining pick time of runoffs is essential for designing watershed management practices in an area. In this study, physical characteristics with rainfall and runoff data for a thirty-year period (1986-2010) were studied in eleven forth order watersheds in Ardabil, Iran. The watersheds surface areas vary from 257 to 2184 km2 and their slopes are between 16.25% and 33.3%. Significant differences were found among their monthly rainfall (p

Stilling basins are the most common energy dissipator structures for depreciation of water energy at super critical speeds, typically are used at down stream of hydraulic structures such as dams and chutes and also in structures of irrigation and drainage networks. A new method using a stilling basin with indented bed and adverse slope, is proposed in this research. The experiments were carried out for upstream Froude numbers in the range of 4.4 to 7.39, with four adverse slopes in the range of zero to -0.02, and also four indented roughness values in the laboratory. The results showed the average decreases of 35 and 49 percent on sequential depths and the relative length of a hydraulic jump, also the average increases of 21 and 14 percent on energy loss and coefficient of bed shear stress of hydraulic jump, respectively, which could reduce the administrative costs of stilling basins.

Bandal-like structure is a kind of a spur dike which is a combination of a permeable and an impermeable spur dikes that are usually used in Indian Sub-Continents for riverbank protection and improvement of navigation conditions in alluvial rivers. It is considered as a suitable alternative for these spur dikes. In this research effect of the submergence and angle of the bandal-like structure on the maximum scour depth in a 90 degrees’ mild bend flume was investigated. Therefore, a series of bandal-like structures were placed in the flume with three different angles (60, 90, 120) and three different submergence ratios (1.16, 1.65, 2.15) and were examined under four different Froude numbers (0.21, 0.23, 0.26, 0.29). The results showed that the maximum and minimum scour depths belonged to the bandal-like structures with 90 and 60 degrees angles respectively. Also by increase of the submergence ratio the maximum scour depth was increased.

Salinity is a widespread problem and a limiting factor on the development of urban landscape in arid regions. Due to lack of good quality water in these areas, there is a noticeable to use of low quality water for irrigation of plants. In this regard, introduction of salt tolerant species for using in urban landscape is necessary. In order to investigate the effects of five levels of irrigation water salinity, including: 0.4, 3, 6, 9 and 12 dS/m-1 on some physiological attributes of Nerium oleander under greenhouse condition, an experimental was conducted based on randomized complete block design with three replicates. The results showed that the all salinity levels caused significant increase of sodium concentration and reduction of potassium in root in comparison with the control treatment. The amount of sodium in leaves of Nerium oleander only at the 12 dSm-1 concentration level had a significant difference with control. On the other hand the potassium concentration in Nerium oleander leaves was not affected by the salinity. Also the leaf Proline concentration was increased with increasing salinity, but there was no significant difference in the amounts of soluble sugars and chlorophyll between different treatments. So, it seems Nerium oleander by the Proline aggregation and also absorption and holding the sodium and chlorine in the roots and preventing their translocation to the leaves, can tolerate salt stress.

Side weirs are of main hydraulic structures which are widely used in flow diversion systems and drainage networks. Also, circular channels are used as the main channel for flow transmission in sewage disposal systems and irrigation networks. In this study, pattern and field of the passing flow within circular channel along the side weir under supercritical flow regime was simulated using FLOW-3D software. Also, the flow field turbulence and variations of the free surface have been simulated using RNG k-e turbulence model and VOF scheme, respectively. Comparing numerical simulations with experimental results showed the reasonable accuracy of numerical model. In practice, transport channels used in irrigation networks and urban sewage disposal are steep. Therefore, the effect of bed slope variations on the hydraulic characteristics of flow field along the side weir was investigated. By increasing the main channel bed slope the free surface of flow along the side weir was decreased. According to simulation results, by increasing the circular channel bed slope the specific energy was increased.

For zoning of wheat grain yield, simple kriging, cokriging and regression- kriging methods were evaluated. For this purpose, in 2014, 298 rainfed wheat fields with distances of 0.59 km from each other were selected at the Khodabandeh county located in the south of Zanjan province. Wheat grain yield of the rainfed lands was measured using the quadrant plots in the field. Soil samples were collected from the surface soil (0-30 cm) of the fields at two replicates. Physical and chemical properties of soil including sand, silt, clay, moisture, organic matter, pH, EC, calcium carbonate equivalent, total nitrogen, available phosphorus and plant-available potassium were measured. Soil data were used to assess the geostatistical models and evaluate the soil characteristics roles on wheat grain yield over the fields. Out of total data, 238 data were used to develop geostatistical models and 60 data were applied to test the models. Results showed that cokriging estimated wheat grain yield in new locations more accurate (R2= 0.74, RMSE= 118.95) than the simple kriging (R2= 0.74, RMSE= 127.87) and regression- kriging (R2= 0.26, RMSE= 198.84). Soil total nitrogen was used as auxiliary variable in cokriging method to determine the spatial variation of wheat grain yield. In addition, according to the results by understanding the spatial variation of the soil total nitrogen spatial grain yield variation can be quantified and used as geostatistical map for management scopes.

Local scour is one of the main drivers of instability and failure of bridge piers. Therefore, in addition to the stability issue, the scour depth reduction is also important. Numerous solutions have been presented for scour depth reduction. In this study, a new idea environmentally-friendly and non-structural approach has been introduced for bridge pier scour depth reduction. Nano-structured materials are waterproof, they can be used for scouring reduction in alluvial beds. For achievement of research aims, the bed sediment around the bridge pier was mixed with some nano-structured material called nanoclay. The experiments were carried out in a laboratory flume under steady conditions on a cylindrical bridge pier. The obtained results showed that, the highest scour depth reduction percentage (58.3%) occurred for the largest flow discharge (16 L s-1) by a large difference compared to other values of flow discharge. In this case, the scour depth was decreased from 60mm to 25mm due to presence of nano-structured material. The lowest percentage of scour depth reduction was nearly 41.6 for the minimum flow discharge (4 L s-1).

Soil surveying and land suitability are essential for conducting an applied research and acquiring land and soil characteristics information. The aim of this study was to detect appropriate zones for some chosen agricultural and horticultural plants in current and future conditions. The studied region with an area of 295 hectares was located at Abyek region in Qazvin province. Soil moisture and temperature regimes were Weak Aridic and Thermic, respectively. Alluvial fan and piedmont plain were predominant physiographics that were leveled for agricultural purposes. Nine soil profiles were described and classified based on soil taxonomy,which were placed in Aridisols and Entisols order. Current and future land suitabilities were surveyed taking into account of the climate, soil and land conditions for five land utilitization type (including: autumn canola, tomato, apple, pear and walnut). The results showed that existence of relatively large amount of stone, gravel, rubble, carbonate calcium equivalent and soil pH were the most important limitation factors for different utilization types. For tomato and walnut, land suitability class couldn’t be promoted to S1 (no limitation). It was because of climate condition of the region that was more or less restrictive for them. However, land suitability class for other LUTs could be improved by implementing suitable land management practices. Also, 40% and 43% of the total study area were suitable (S1) for horticultural and irrigated agricultural use, respectively. Finally, due to high limitations, the remaining 17% of area could be used for non-agricultural purposes.

Phytoremediation is a technique for removal of heavy metals including cadmium (Cd) from soils; which is less expensive compared to other methods. Due to the fact that this method is time consuming with low efficiency, hence, other methods are proposed to increase the efficiency of phytoremediation. One method is the application of organic residues to the soils. A greenhouse experiment was conducted to study the effects of the application of wheat or alfalfa residues on phytoremediation of Cd-contaminated calcareous soil by corn. The experiment was a factorial 2×3×3 arranged in a completely randomized design. Treatments consisted of the two types of the organic residues (wheat and alfalfa) in three levels (0, 1, and 2% by weight) and three levels of Cd application (5, 15, and 25 mg kg-1) with three replications. Results indicated that increasing the Cd levels, significantly increased the Cd concentration in soil and in the corn shoots, but decreased the dry weight of the corn and bio-accumulation factor (BAF) of Cd. Increasing the levels of wheat and alfalfa residues significantly increased the Cd concentration in the corn shoots and BAF. Addition of the wheat residues resulted in a higher Cd concentration in the corn aerial parts and BAF compared to those with addition of the alfalfa. However, the corn mean shoot dry weight was significantly higher in the soil amended with the alfalfa residues compared to those amended with the wheat residues. Influences of the wheat or alfalfa residues addition on the Cd uptake by corn were similar. Phytoremediation efficiency of the corn at low Cd levels was higher than that at high rates of the applied Cd.

Applying multivariate models in describing and modeling complicated hydrological events has been recommended by hydrologists in the recent three decades. In fact, employing effective factors in the multivariate models can improve the results of describing, modeling and predicting different variables. Furthermore, nonlinear conditional heteroscedastic models can be used for modeling linear residual part of time series and it is expected that combining the linear and nonlinear models increases the accuracy of modeling and forecasting results. In this study the two multivariate periodic ARMA and multivariate combined with the conditional heteroscedasticity models were compared and used to model Nazloochai River discharge located at the West Azerbaijan Province by considering air temperature and precipitation variables during the period of 1962-2011.The results of the models evaluations and verifications showed that both of the models had acceptable accuracy in modeling of the river flow discharge. Also results indicated that the combined conditional heteroscedasticity multivariate models involving the effective parameters of river flow series had more accuracy than multivariate periodic ARMA model. The both models estimated the maximum and minimum points of discharge series correctly. Also the results showed that by combining two multivariate periodic ARMA and nonlinear autoregressive conditional heteroscedastic models the error was decreased about 16% in comparison with the error of the periodic ARMA model.

Nowadays, Water and solute transport simulations in different irrigation methods are evaluated using different models. The purpose of this study was to compare the simulation results of HYDRUS-2D model for different furrow irrigation treatments with field experiments. Treatments included Conventional Irrigation (CI), Fixed Partial Root Irrigation (FPRI) and Deficit Irrigation (DI). Root Mean Square Error (RMSE) values were calculated in the range of 0.03 to 0.05 (cm3 cm-3) for the estimated water content in the treatments. According to the simulation results, after a period of a 10 days, the distribution of moisture around the root zone was in the range of the readily available water content, so it was possible to increase irrigation interval up to 13 days instead of 10 days. Estimated nitrate values of FPRI and DI treatments showed an overestimation in comparison with the measured values. The potential for nitrate leaching at 40 cm depth would be estimated in the order of CI> DI>FPRI for different treatments. Thus, more nitrogen was available to the plant in deficit irrigation treatments (DI, FPRI). Therefore, HYDRUS-2D model is advisable as a powerful tool in the simulation and management of water and solute consumptions in the furrow irrigation.

Since field researches for evaluating drain envelopes are costly and time consuming, laboratory evaluation of these envelopes is a suitable approach. The main goal of this study was obtaining a set of empirical equations in order to estimate the hydraulical and clogging parameters using hydraulic head and drain outflow (which are easy to measure) and removing the effect of piezometers installed in the permeameter body. To conduct this research, a permeameter was designed and made according to ASTM-5101 standard. Then, three types of commonly used geotextile filters, e.g. PP-450, PP-700 and PP-900 were used. The required soil for this experiment was collected from a drainage project in the north of Khorramshahr at 1.65 m depth. The test was conducted in the laboratory using Permeameter by producing 4 different hydraulic pressure heads (25, 50, 75, 100 cm). Special parameters (envelope hydraulic conductivity, soil hydraulic conductivity, soil-envelope hydraulic conductivity, gradient ratio) were calculated by measurement of hydraulic head, outflow and piezometers installed in the permeameter body. Results showed that these models gave accurate estimation of the assessed parameters. High correlation coefficient values of these equations (for three synthetic envelopes PP450, PP700 and PP900) indicated that they provided an accurate estimation for soil-envelope hydraulic conductivity, soil hydraulic conductivity, envelope hydraulic conductivity and gradient ratio. Using the suggested equations clogging and hydraulic performance of drainage envelopes in different conditions can be simulated.

Addition of organic residues to soil in organic farming may change soil K status and subsequently its availability and cycling. For this purpose, an experiment was done as factorial in completely randomized design with application of 11 organic materials (alfalfa, barley, pea and broad bean residues and sheep, cow, camel, poultry, pigeon and quail manures and vermicompost) in two clayey soils of Darab and Sepidan (Fars province) under two moisture conditions (field capacity and saturation) with three replicates. First, 2 g of organic materials was added to 100 g of soil samples and incubated for two months under field capacity and saturation conditions and laboratory condition (22±2˚C) and then the contents of soluble, exchangeable and non-exchangeable K were determined. Results indicated that all organic materials, except for vermicompost, alfalfa residue and camel manure increased soluble K and the highest increase was related to sheep manure up to 228 mg kg-1. The content of exchangeable K was increased with all organic residues application from 70 to 730 mg kg-1. The content of non-exchangeable K was also increased with organic residues application and the highest and lowest increases were found for poultry manure and camel manure, respectively. Generally, the contents of soluble and exchangeable K of Darab soil and non-exchangeable K of Sepidan soil were more affected by organic materials application. The saturation condition increased exchangeable K and decreased soluble and non-exchangeable K. Increase in the content of soluble K and soil salinity should be considered for organic amendments application to soils with high leaching potential and for salt sensitive plants.

Study of the relations between measured variables at meteorological stations and mountain basins’ surface runoff is useful in flow modeling. In this study, to investigate the effects of time series of the recorded meteorological variables at Sahand synoptic station on the amount of snowmelt and runoff in the Lighvan basin, the correlation between these variables and average daily temperature (2001 - 2009) were reviewed to choose the variables those having appropriate correlation with the temperature. Then four index intervals in snowmelt season were determined during the period of Dec. 22nd to Jun. 21st. The correlation between the related variables and daily runoff with different lag times were examined and the variables with the highest correlation were selected. Regression equations were applied on the selected variables and then they were validated with the Liqvan hydrometry station measured runoff values. Due to the optained results, the underground temperature at the depth of 20cm had the best correlation (r = 0.911) with runoff measured values during the period of Dec. 22nd to Jun. 21st while no lag time was considered the relevant series. Also, the lowest correlation (r = -0.476) was obtained for the humidity at time of 3am in the same period with lag times of 4 and 5 days. The results of validatation of the regression models showed that the stepwise regression model had an admissible accuracy (CE = 0.61) in estimation of streamflow in snowmelt season.

In this study, effect of three different openings arrangements of drainage pipes on the drainage water salt load was investigated using a physical model. The first arrangement of openings for drainage of the subsurface flow had four parallel rows on the upper and lower sides of the pipe (M4). In the second arrangement the pipes had three parallel rows of openings with 120 degrees apart between the rows (M3) and the third one had one row of holes on top of the pipe (M1). Drainage pipes were installed at 20 and 60 cm depths with spacing of 60 and 180 cm. The results showed that the M1 and M3 cases experienced a decline in the contribution of the groundwater in the drained water. The M4 case had the highest contribution of the groundwater, while the M1 had the lowest one of that. So, there was a significant difference between the drainage salt loads at M4 and M1cases. In all cases, deep drain installation led to increase the drainage water salt load.

This research was performed to investigate the effects of two kinds of soil amendment materials on the physical-chemical properties of soil and wheat yield as factorial traits in the form of RCBD with 3 replications. Sulfur was applied in 4 levels of 0, 200, 400 and 600 kg-ha-1 and manure was added in three levels of 0, 20 and 40 ton-ha-1. Manure and sulfur were added in the first year of the experiment and in the second year the effects of these factors on soil properties and yield were studied. The results showed the interaction effect of sulfur and manure was meaningful on grain yield and harvest index. The maximum grain yield 5249 kg-ha-1 was obtained with consumption of 600kg Sulfur-ha-1 along with 20 ton manure –ha-1. Consumption of 40 ton-ha-1 manure decreased pH from 7.53 to 7.30, ρb from 1.49 to 1.26 g-cm-3 and increased EC from 0.92 to 1.2 dS-m-1 and OC from 1.05 to 1.49%. Based on the results of this research, the consumption of 600 kg/ha sulfur and 20 ton-ha-1 manure is appropriate to increase or promote quality and quantity of the yield of wheat and to improve soil properties.

Precipitation information plays an important role in water resources and natural resources studies in any region. With respect to the large changes in the spatial and temporal distribution of precipitation in the arid and semi- arid areas, it is important to regionalize precipitation. One of the methods for regionalization of precipitation is application of deterministic and geostatistical methods. In this research, different methods, namely, inverse distance, local polynomial, radial basis function, simple kriging and ordinary kriging were assessed using different models for regionalization of seasonal precipitation in Hamadan Province utilizing the precipitation statistics of 20 meteorological stations belonging to the Meteorological Organization and Ministry of Energy for a 10-year period (2003-2012). For assessing the performance of the examined methods the cross validation method, the assessment criteria Mean Absolute Error, Root Mean Squared Error and General Standard Deviation index were utilized. The results showed that the radial basis function method with Thin Plate Spline model for the autumn, the inverse distance weighting method for the winter and spring, and the radial basis function with Completely Regularized Spline model for the summer were the most appropriate methods for regionalization of the seasonal precipitation in Hamadan Province.

In order to determine effective parameters on Aji Chay river pollution and the aquifer of Tabriz plain located in eastern part of Urmia Lake and better management and controlling of water resource quality, principal component analysis, artificial intelligence techniques (neural networks and decision tree M5) and geostatistics (Kriging and Cokriging) through water quality data analysis (Cations, Anions) in the period of 2001 to 2013 have been used. Statistical multivariate analysis has an ability to process a big range of data, and is known as a quantitative method in order to manage water quality of the East Azarbaijan province’s rivers. Determination of the water quality parameters would result in costs reduction and aiming the monitoring, controlling, and protection of water quality. The results show that M5 method presents simple linear relations in predicting chloride and salinity, also the decisions for categorizing decision tree algorithms are clear and extractable. Also the results of geostatistics showed that Tabriz plain's aquifer is in a bad condition from qualitative viewpoint compared to the last years, and in western part of the plain due to extreme well extraction, salinity in outlet from 9000 in 2001 to over 11000 (µmhos cm-1) in 2012 has been increased.

Considering the dynamic and nonlinear nature of river flow, it is expected that the river flow time series is obtained from a deterministic chaotic system. Since that the time series obtained from the natural phenomena are generally contaminated by noise, the presence of noise limits the chaotic analysis and consequently makes limitations in the prediction of time series. For this reason, in this study the chaotic analysis, including the evaluation of the presence of chaos using correlation dimension and simulating the river flow using Local Approximation Method, was investigated on daily series of Nazluchay River during the 1990 to 2012 period. Afterwards, in order to evaluate the noise effect on the process of analysis, noise reduction of time series was carried out by a nonlinear method based on phase space reconstruction. The results showed 6.07% decrease in correlation dimension and an increase in model accuracy for the noise reduced time series with respect to the original series (1.09% increase in R2 and 48% decrease in RMSE). Finally, by the selected simulation model, prediction of the river flow was done using the original and noise reduced time series for the 2012-2013 period. The model results predicted with the noise reduced series were found to be more accurate than those with the original series.