Research Article
Research Article
S. Porbakhshian; M.R. Majdzadeh Tabatabaei; S.S. Mousavi; Sh. Mansouri
Abstract
Abstract
Morphological river models are designed to provide physical insight into the morphological response and to assist river engineers and managers in the design, operation and maintenance of river systems. Here deterministic modeling weak for a dynamic and stochastic of nature river environment. ...
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Abstract
Morphological river models are designed to provide physical insight into the morphological response and to assist river engineers and managers in the design, operation and maintenance of river systems. Here deterministic modeling weak for a dynamic and stochastic of nature river environment. Specially, these could not predict the exact shape of the river bed, Specially e.g. for braided river because the bed level variability and variations in cross-sectional. Since a stochastic model approach copes with the variability of system behavior of the time, therefore need for Stochastic modeling on the location of morphological changes in rivers and variations in river bed seems necessary. Many large rivers in the world have recently undergone through a great deal of morphological changes, Which has led to the development of local scouring, therefore, it has become an important problem for the river engineering. The change of river morphology is evaluated by braid parameter in braided rivers. A decrease in braid parameter results in a braided channel changes to meandering. As a result, local scouring process is accelerated. Since Process of the changes in river cross section are usually caused by change in water and sediment discharges or by river works. Moreover, river gradient plays a key role in channel morphological changes therefore In this research, local scouring relationship with river morphologic changes are investigated by stochastic modeling in braided rivers based upon for parameters such as maximum water, sediment discharges, river bed gradient river and bed elevation. The model was then tested by data obtained from Yahagi river in Japan. That the month Maximum Stream flow data is predicted by time series models (ARIMA) and three sediment transport equation were used to calculate the bedload such as Bagnold, Meyer-peter and Einstien Brown. predicted results show If calculate the bedload with the Bagnold equation, this model could predict significantly in cross-sectional and local scour depth, predict river morphological changes.
Keywords: Braided river, Local scouring, Stochastic modeling, ARIMA, Non linear variant regression
Research Article
M. Daryaee; S.M. Kashefipoor
Abstract
Abstract
Due to the importance of using clay soil in many constructive projects such as, road foundation, irrigation canals and related hydraulic structures and etc., improvement of the physical and mechanical soil properties has been the main interest of the geo-technique specialists for years. In ...
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Abstract
Due to the importance of using clay soil in many constructive projects such as, road foundation, irrigation canals and related hydraulic structures and etc., improvement of the physical and mechanical soil properties has been the main interest of the geo-technique specialists for years. In this regard different methods such as mixing clay soil with lime or cement have been used. It has been found that adding some other materials such as polymeric material and sand can more improve the properties of clay-lime mixture. In this research the effect of adding soft sand on the clay-lime properties has been investigated. The soil sample was mixed with 0%, 3%, 5%, 7%, and 9% of lime and 0%, 5%, 10% and 15% of soft sand, and totally a number of 20 samples were provided. The samples after maintaining under three periods including, 7, 14 and 28 days, saturation conditions and temperature of 25°C were tested with the unconfined compressive strength instrument. The main results of this research showed that adding only soft sand to the soil could not improve the soil properties, but using it with lime could significantly improve the soil geotechnical properties. It was found that the best mixture for the highest unconfined compressive strength and elasticity module is the a mixture of original soil with 7% and 10% of lime and soft sand respectively.
Keywords: Clay soil, Lime, Soft sand, Unconfined compressive strength, Eelasticity module
Research Article
A. Eskandari; H.R. Khazaie; A. Nezami; M. Kafi
Abstract
Abstract
In order to study the effects of irrigation regimes on yield and some qualitative characteristics of three cultivars of potato (Solanum tuberosum L.), an experiment was conducted in 2009 in the research field of the College of Agriculture, Ferdowsi University of Mashhad. A factorial experiment ...
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Abstract
In order to study the effects of irrigation regimes on yield and some qualitative characteristics of three cultivars of potato (Solanum tuberosum L.), an experiment was conducted in 2009 in the research field of the College of Agriculture, Ferdowsi University of Mashhad. A factorial experiment was arranged in a randomized complete block design with three replications. Experimental factors were three irrigation regimes including: I1: 100% of water requirement of potato in Mashhad, I2: 70% of water requirement of potato in Mashhad applied before tuber initiation and I3: 70% of water requirement in Mashhad applied at all growth period of potato and the used cultivars were Agria, Almera and Sinora. The results indicated that in all irrigation regimes, Agria was better in tuber yield and number of marketable tuber compared to other cultivars and also had the highest amount of mean marketable weight tuber and starch percentage, whereas Almera had the highest significant dry matter compared to other cultivars. Also with increased in irrigation level, all quantitative and qualitative characteristics except tuber specific gravity weight improved. So concerning to the result of this experiment, with 30% decrease in volume of applied irrigation water before tuber initiation, a fairly significant yield can be expected for Agria compared to other cultivars.
Keywords: Potato, Irrigation regimes, Cultivar, Marketable tuber
Research Article
Sh. Gholami; S.M. Hosseini; J. Mohammadi; A. Salman Mahiny
Abstract
Abstract
Soil invertebrate and their spatial pattern are affected strongly by environmental factors. Spatial variability of soil properties is one of the most important reasons of the macrofauna variability. This study was conducted to investigate the spatial variability of soil properties and soil ...
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Abstract
Soil invertebrate and their spatial pattern are affected strongly by environmental factors. Spatial variability of soil properties is one of the most important reasons of the macrofauna variability. This study was conducted to investigate the spatial variability of soil properties and soil macrofauna biomass in the riparian forest landscape of Karkhe River. Soil macro fauna were sampled using 200 sampling point along parallel transects (perpendicular to the river). The sampling procedure was hierarchically, maximum distance between samples was 0.5 km, but the samples were taken at shorter distance at different location of sampling. Soil macro fauna were extracted from 50 cm×50 cm×25 cm soil monolith by hand-sorting procedure. At each transect point, approximately 1m distance from the macro fauna sample location, three 50 cm×50 cm×25 cm samples were taken from 0-25 depth of soil. Soil macro fauna biomass, pH, EC and soil texture were measured. Then the spatial continuity, using geostatistics (variogram) were described. The maps obtained by block kriging. The variograms of variable revealed the presence of spatial autocorrelation. The range of influence was 1728 m for macro fauna biomass, 1800 m for pH, 1536 m for EC, 2964 for sand (%), 2100 for silt (%) and 3264 for clay (%).The kriging maps showed that the soil macro fauna biomass and soil properties have spatial variability. In this research, the spatial pattern of soil macro fauna biomass is similar with the spatial pattern of silt and soil pH, that was shown in correlation.
Keywords: Spatial pattern, Soil macrofauna biomass, Soil properties, Variogram, Block kriging
Research Article
A.R. Gholami; N. Pirmoradian
Abstract
Abstract
The application of the crop growth models could facilitate irrigation water and fertilizer management due to reduce of field visits and direct measurements. These models are often so complex that it is difficult to understand them and some of those input data are not accessible. In this study, ...
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Abstract
The application of the crop growth models could facilitate irrigation water and fertilizer management due to reduce of field visits and direct measurements. These models are often so complex that it is difficult to understand them and some of those input data are not accessible. In this study, a simple model (VSM) was used to yield prediction of corn under different water and nitrogen managements. In calibration process, the model parameters including maximum leaf area index, flowering and harvest time period, harvest index, and light use efficiency were estimated based on irrigation water and nitrogen application. The model was calibrated using data from a corn field experiment that involved a split-plot factorial design with three replications, four irrigation treatments and four nitrogen application rates. Comparing of the measured and estimated values showed that the model could successfully estimate the yield for experiment data. The validated model can be used in managing of water and nitrogen for corn cultivation. However, it could be determined the optimum level of inputs before starting of the growth season.
Keywords: Model calibration, VSM model, Water, Nitrogen, Corn
Research Article
E. Malekzadeh; H.A. Alikhani; Gh.R. Savaghebi; M. Zarei
Abstract
Abstract
In this study, interaction between AMF (G. mosseae and Glomus spp., respectively indigenous and non-indigenous of HM-contaminated areas) with Cd-resistant PGPRs (Bacillus mycoides and Micrococcus roseus, indigenous of contaminated areas) on the growth, Cd and nutrient uptake of maize plant ...
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Abstract
In this study, interaction between AMF (G. mosseae and Glomus spp., respectively indigenous and non-indigenous of HM-contaminated areas) with Cd-resistant PGPRs (Bacillus mycoides and Micrococcus roseus, indigenous of contaminated areas) on the growth, Cd and nutrient uptake of maize plant (Zea mays L.) in Cd polluted soil were investigated. With increasing levels of Cd, shoot and root dry weights, shoot Fe and P contents decreased but root and shoot Cd content increased. Root colonization was varied at different levels of Cd and co-inoculation with PGPRs. G. mosseae treatment had greatest amount of shoot and root dry weight, Fe and P of shoot at high concentration of Cd. At the levels of 100 and 200 Cd, in only mycorrhizal treatments, plants colonized by Glomus spp. and G. mosseae had respectively high content of Cd roots. At both levels of Cd, shoot Cd content in co-inoculation of M. roseus and B. mycoides with G. mosseae increased and decreased respectively in comparison with single inoculation of G. mosseae. While, at the levels of 100 and 200 Cd, shoot Cd content in co-inoculation of PGPRs with Glomus spp. respectively increased and decreased/did not significant different compared to single inoculation of Glomus spp. Co-inoculation of G. mosseae and M. roseus, with maximum Cd-accumulated in plant, was the most effective treatment in Cd phytoremediation and stabilization.
Keywords: AM fungi, Plant growth promoting rhizobacteria, Phytoremediation, Cd and maize
Research Article
H. Ansari; H. Moradi
Abstract
Abstract
Evapotranspiration as one of the most important components of the hydrologic cycle, plays a key role in water resources management, crop yield simulation and irrigation scheduling. Therefore, presenting a low cost and precision model is very essential for calculations of hourly ETo. Although, ...
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Abstract
Evapotranspiration as one of the most important components of the hydrologic cycle, plays a key role in water resources management, crop yield simulation and irrigation scheduling. Therefore, presenting a low cost and precision model is very essential for calculations of hourly ETo. Although, there are empirical formulas, their performances are not all satisfactory due to the complicated nature of the hourly evapotranspiration process, the data availability, and high cost and error for gathering data. This paper develops hourly ETo estimation model based on fuzzy inference system (FIS) technique. We follow the idea of using the least input parameters, so the net radiation (Rn) selected, as the only input parameter. The used data has been picked on UC-Andrade station for training model, that have the most variation on Rn and climatically conditions, and another thirteen stations, that selected randomly, among 114 automated stations in US California. There is not proper hourly data in Iran. FIS model estimates hourly ETo as crisp number using of 230 rules with 48 level, centeroid defuzzification method and inference Mamdani method. FIS results compared with Penman-Monteith-FA056 and CIMIS-Penman combined model. It has been found that FIS technique has high accuracy and good performance (for the train data set, R2 = 0.97, RMSE= 0.07, MBE=-0.004 and R2/t (t: Jacovides criteria)=0.21). Comparing FIS with CIMIS and FAO56 results shows that FIS has better correlation with CIMIS than FAO56 for test data set, with R2 = 0.94, RMSE= 0.0693, MBE=-0.0384 and R2/t=0.018. Among FIS, CIMIS and FAO56, FIS model is economical, because of the parsimony principal; in conclusion, it raises model accuracy.
Keywords: Fuzzy model, Hourly Evapotranspiration, CIMIS-Penman, Penman-Montieth-FAO56
Research Article
A.H. Khoshgoftar Manesh; E.S. Razizadeh; H.R. Eshghizadeh; Gh.R. Savaghebi; A. Sadrearhami; D. Afuni
Abstract
Abstract
This study was conducted at Rudasht Research Farm in Isfahan to evaluate tolerance to zinc (Zn) deficiency of 30 spring wheat genotypes, using split plots in a randomized complete blocks design with triplications. Main plot consisted of two Zn levels (Zero and 80 kg Zn ha-1 applied as zinc ...
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Abstract
This study was conducted at Rudasht Research Farm in Isfahan to evaluate tolerance to zinc (Zn) deficiency of 30 spring wheat genotypes, using split plots in a randomized complete blocks design with triplications. Main plot consisted of two Zn levels (Zero and 80 kg Zn ha-1 applied as zinc sulfate at planting). The results of ANOVA as well as correlations between tolerance and susceptibility indices to Zn deficiency stress and grain yield indicated that MP, GMP and STI were the most suitable indices for identifying and selecting Zn-deficiency tolerant wheat genotypes. Both at with and without added Zn treatments, grain yield had significant positive correlation with MP, GMP and STI. The STI could separate the studied wheat genotypes in different groups based on both their response to fertilization and grain yield potential. Therefore, the STI was the best index to identify Zn deficiency tolerant genotypes. Based on three indices, Ghods and Falat genotypes were the most tolerant and sensitive genotypes to Zn deficiency, respectively.
Keywords: Stress indicator, Wheat, Zinc efficiency, Tolerance
Research Article
R. Ghobadian
Abstract
Abstract
Due to transmission losses and lack of initial flow, flood routing in ephemeral streams is not possible with common methods and it is necessary the flood routing models have been developed for these streams. Therefore in this study a computer model for natural river cross section has been ...
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Abstract
Due to transmission losses and lack of initial flow, flood routing in ephemeral streams is not possible with common methods and it is necessary the flood routing models have been developed for these streams. Therefore in this study a computer model for natural river cross section has been developed in that after linearization of partial differential equations of unsteady none uniform flow, they are solved by stagger method. This model can consider tributary flow and infiltration into river bed simultaneity. For estimation of transmission losses Muscat, Davis-Wilson, and Ingham methods have used and liked with unsteady flow equations in prepared model. Evaluation of model accuracy viewpoint programming, ability to simulate uniform flow and satisfying the continuity equation performed using 60 Garasoo River cross sections in a reach with about 18 km length. Lane’s hydrograph and Hughes Wash river properties were used to investigation model accuracy to estimate flow behavior and transmission losses. The result showed that prepared model can simulate uniform flow and satisfies continuity equation with height accuracy. Additionally when Muscat relation is used developed model can predict start and peak flood times correctly. Also transmission losses and volume of output hydrograph have predicted with maximum error less than 20 percent. While application of Davis – Wilson and Ingham relations showed unsatisfied result compare in situ measurement data.
Keywords: Transmission losses, Ephemeral stream, Flood Routing, Saint-Venant equations
Research Article
J. Kermannezhad; M. Fathi Moghadam; A.A. Dehghani; M. Mahmoodian
Abstract
Abstract
The groines are structures which are use to protected the river bank and to form the water way .The most important problem of groynes is scour at around it that makes breaking and overturning the groynes. Because of the less researches at about L-head groynes and open groynes ,this article ...
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Abstract
The groines are structures which are use to protected the river bank and to form the water way .The most important problem of groynes is scour at around it that makes breaking and overturning the groynes. Because of the less researches at about L-head groynes and open groynes ,this article considers the amount of scour in this type of groynes. So because of this have been used the lace gabions full of rock for producing the open groynes and considered effect the amount of porosity of gabion on scour of L-head groyne with clapper to down stream. Results show that for 40-50% of porosity, lower scour at around groin with clapper toward downstream occurs and the maximum scour around The groin with clapper toward upstream can be observed.
Keywords: L-head, Groyne, Gabion, Scour, Clear water
Research Article
M. Golmohammadi; A. Massah Bavani
Abstract
Abstract
This research evaluates climate change effects on drought severity in the region of Gharesou, Iran. The Standardized Precipitation Index (SPI) has been used for estimation of drought severity. A geographical information system is applied for calculating the mean areal precipitation time series ...
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Abstract
This research evaluates climate change effects on drought severity in the region of Gharesou, Iran. The Standardized Precipitation Index (SPI) has been used for estimation of drought severity. A geographical information system is applied for calculating the mean areal precipitation time series from 11 meteorological stations, in and out of the area for the hydrological period Jan 1971-Dec 2000 using Inverse Distance Weighting method. This precipitation time series have been used for the estimation of Standardized Precipitation Index (SPI) for three timescales, 6, 12 and 24 months, for the region. The outputs of HadCM3-A2 were applied for the assessment of climate change impact on droughts. The HadCM3 outputs were downscaled statistically to the region of Gharesou using SDSM software to estimate precipitation time series for a future period 2040-2069. A method has been used for the estimation of annual cumulative drought severity-time scale-frequency curves. These curves integrate the drought severity and frequency for various types of drought. The SPI time series were estimated and compared with the respective time series of the historical period 1971-2000. The comparison indicated that the annual drought intensity decreases for the three examined SPI time series. Furthermore, analysis of drought period has shown that value and frequency of drought would be declined in future in the region.
Keywords: Climate Change, Drought, SPI, HadCM3, Gharesou Basin
Research Article
M. Rasouli-Sadaghiani; E. Sepehr
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Abstract
Biological and chemical changes in rhizosphere following organic residues as well as manures application are important processes which influence nitrogen mineralization and nutrients bioavailibity in soils. This study was done to evaluation of organic residues effect on growth, nitrogen supply ...
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Abstract
Biological and chemical changes in rhizosphere following organic residues as well as manures application are important processes which influence nitrogen mineralization and nutrients bioavailibity in soils. This study was done to evaluation of organic residues effect on growth, nitrogen supply and rhizosphere characteristics of corn and sunflower plants in greenhouse experiment using sewage sludge (SS), poultry (Pl), cattle (Ct) and sheep (Sh) manures. The results showed plants acquired significantly more N, P, K, Ca, Mg, Fe, Mn, Zn and Cu in SS treatment than other manures. Sunflower in comparison with corn plants showed higher N, P, K, Ca and Cu uptake, which can be attributed to its higher nutrient-uptake efficiency. The highest mineralized nitrogen in rhizosphere and non-rhizosphere soil were achieved in Pl (214.8 mg kg-1) and SS (227.5 mg kg-1), respectively. Mineralized N in particular nitrate was observed at high concentration in rhizosphere compared to non-rhizosphere soil, which indicate higher microbial activity including nitrificators and high mineralization processes in sunflower rhizosphere. Net nitrogen mineralization (Nm) in rhizosphere was higher than that in non-rhizosphere which the microbial population in corn and sunflower rhizosphere were 3.7 and 2.3 times higher than non-rhizosphere soil, respectively . Treatments applied with SS showed the highest microbial activity compared to other organic residues. At rhizosphere, net nitrogen mineralization was occurred in Pl and SS treatments whereas Ct and Sh applied soil showed nitrogen net immobilization. Except for SS, all applied residues showed net immobilization in non-rhizosphere soil. The highest total mineralized N (mineralized N exist in soil and absorbed N by plants) were as fallows in treatments: Pl> SS> Sh> Ct.
Keywords: Sewage sludge, Manures, Nitrogen mineralization, Rhizosphere
Research Article
A. Sepahvand; M. Taie Semiromi; Kh. Mirnia; H.R. Moradi
Abstract
Abstract
Infiltration is one of the most important phenomena which is affected by the soil physical and hydraulic characteristics. Measurement of infiltration needs the high cost and is time consuming, therefore estimation of infiltration is necessary. Also, due to variability of soil moisture, it is ...
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Abstract
Infiltration is one of the most important phenomena which is affected by the soil physical and hydraulic characteristics. Measurement of infiltration needs the high cost and is time consuming, therefore estimation of infiltration is necessary. Also, due to variability of soil moisture, it is important to determine the appropriate model for the estimating the infiltration rate. The present study was carried out for determining the sensitivity of infiltration models including Kostiakov, Philip, Horton, Soil Conservation Service (SCS) and modified Green – Ampt models at different levels of the soil moisture. To consider the homogeneity of soil and slope, this research carried out in Mour Mouri region, of Ilam province. In this study the infiltration rate was measured by using Double Ring Infiltrometer in the prepared plats (1 m2) at four levels of soil moisture, including control (0), 5, 10 and 15 liters. Afterward the best model was selected by some criteria of error assessment, such as percentage of relative error (RE), root mean square error (RMSE), modeling efficiency coefficient (EF) and coefficient of determination (R2). The results showed that generally, the Kostiakov model can estimate the infiltration rate better than other infiltration models with increasing the soil moisture, the precision of Horton model increased.
Keywords: Infiltration, Models infiltration, Double Ring Infiltrometer, Mour Mouri region
Research Article
V.R. Jalali; M. Homaee
Abstract
Abstract
Saturated hydraulic conductivity (Ks) is needed for many studies related to water and solute transport, but often cannot be measured because of practical and/or cost-related reasons. Nonparametric approaches are being used in various fields to estimate continuous variables. One type of the ...
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Abstract
Saturated hydraulic conductivity (Ks) is needed for many studies related to water and solute transport, but often cannot be measured because of practical and/or cost-related reasons. Nonparametric approaches are being used in various fields to estimate continuous variables. One type of the nonparametric lazy learning algorithms, a k-nearest neighbor (k-NN) algorithm, was introduced and tested to estimate saturated hydraulic conductivity (Ks) from other soil properties including soil textural fractions, EC, pH, SP, OC, TNV, ρs and ρb. A number of 10 nearest neighbors, based on Cross Validation technique were selected to perform saturated hydraulic conductivity prediction from 151 soil sample attributes. The nonparametric k-NN technique performed mostly equally well, in terms of Pearson correlation coefficient (r=0.801), modeling efficiency (EF=0.65), root-mean-squared errors (RMSE=71.15) maximum error (ME=120.47), coefficient of determination (CD=1.32) and coefficient of residual mass (CRM=-0.046) statistics. It can be concluded that the k-NN technique is a competitive alternative to other techniques such as pedotransfer functions (PTFs) to estimate saturated hydraulic conductivity.
Keywords: k-nearest neighbor (k-NN), Modeling, Saturated hydraulic conductivity
Research Article
A.R. Emadi; A. Mohammadiha; J. Mohammad Vali Samani
Abstract
Abstract
Area-reduction method is one of the most common experimental methods that determines the sediment distribution in reservoirs. In this method, reservoirs are geometrically divided into four types. For all reservoir types, parameters are achieved based on a limited number of reservoirs which ...
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Abstract
Area-reduction method is one of the most common experimental methods that determines the sediment distribution in reservoirs. In this method, reservoirs are geometrically divided into four types. For all reservoir types, parameters are achieved based on a limited number of reservoirs which leads to large scale errors for prediction of this method. So suitable parameters can be achieved in dams that are in operation and hydrography of reservoir is carried out at least once. In other words the method can be calibrated for the reservoir. In this study initially a computer model based on the area-reduction method was provided using MATLAB software. Then optimization model was prepared using Genetic Algorithm and these two models were combined, finally. The above mentioned model determines area-reduction method parameters, so that the most compatibility occurs between computational and measured values. For calibration and verification of the model at least three measured data are required. Due to lack of enough hydrographic data in Iranian dams, first the model was applied for Altus dam in USA with three hydrographic data. Results showed that there was a significant increase in accuracy of estimation, using optimal parameters. Finally optimal parameters were achieved using this model for Karde dam that had only two hydrographic data available. Then based on optimal parameters sediment distribution of Karde dam was predicted for next years.
Keywords: Sediment distribution, Area-reduction method, Calibration, Genetic algorithm
Research Article
H. Zare Abyaneh; M. Bayat Varkeshi
Abstract
Abstract
From Longley, the various equations for determining the runoff to water management are presented by the researchers that are widely used in hydrologic sciences. In this study by using observational data, was evaluated empirical, artificial neural network (ANN) and ca-active neuro-fuzzy inference ...
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Abstract
From Longley, the various equations for determining the runoff to water management are presented by the researchers that are widely used in hydrologic sciences. In this study by using observational data, was evaluated empirical, artificial neural network (ANN) and ca-active neuro-fuzzy inference system (CANFIS) models in estimation of runoff. For this purpose, by using climatic and physiographic information in three stations of Pole Zamankhan, Ghale Shahrokh and Sade Zayandeh Rood, runoff values were estimated from empirical models and intelligent models were compared to annual runoff values. Input parameters include rain, mean temperature, mininmum temperature and maximum temperature. The results showed that the artificial intelligent models had good accuracy in estimating runoff. Among the empirical methods, method of Di Souza was appropriate. Comparison statistical parameters between methods was showed that mean percent error (MPE) in ANN, CANFIS and empirical method was 7, 12 and 43 percent respectively that confirmed differences of between the methods is significant. Also, CANFIS model did not artificial improve ANN results. The results showed, with reduction of input variables from 4 parameters to one parameter of precipitation, modeling error reaches its maximum value (from MPE=7% to MPE=16%). Versus, the optimal structure of ANN had less sensitivity to remove the mean air temperature parameter (from MPE=7% to MPE=10%(. Therefore, according to empirical models required information limitations and high accuracy of artificial intelligent models, intelligent models application is recommended.
Keywords: Estimation of runoff, Empirical method, ANN, CANFIS, Zayandeh rood Basin
Research Article
S.M.J. Mosavi; S. Nezami; E. Izadi Darbandi; A. Nezami; M. Yousefsani; F. Keykha Akhar
Abstract
Abstract
The aim of this experiment was the study of freezing tolerance of Bellis perennis under controlled conditions and were arranged in a completely randomized design with three replications. Plants after sowing and grow in the bed, at the middle of autumn (after hardening in natural conditions), ...
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Abstract
The aim of this experiment was the study of freezing tolerance of Bellis perennis under controlled conditions and were arranged in a completely randomized design with three replications. Plants after sowing and grow in the bed, at the middle of autumn (after hardening in natural conditions), in the 7-8 leaf stage put on the thermogradiant freezer with the 12 freezing temperatures (0,-2,-4,-6,-8,-10,-12,-14,-16,-18,-20,-22 oC). Cell membrane stability was measured through electrolyte leakage (EL) and survival percentage and regrowth of the plants after 3 weeks in cold frame were measured, by counting the number of plants and determining their proportional with the number of plants before freezing and measuring the dry matter, number of flowers and fully developed leaves. With decreasing the temperature EL increased significantly (P
Research Article
M. Soleymani Nanadegan; M. Parsinejad; Sh. Araghinejad; A. Massah Bavani
Abstract
Abstract
In this study, impact of climate change on net irrigation requirement (In) and yield of wheat using CGCM3 climate projection model, one of the AOGCM models, in Behshahr area is evaluated. changes in temperature and precipitation were simulated run under the IPCC scenario A2 for 2011-2040, 2041-2070 ...
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Abstract
In this study, impact of climate change on net irrigation requirement (In) and yield of wheat using CGCM3 climate projection model, one of the AOGCM models, in Behshahr area is evaluated. changes in temperature and precipitation were simulated run under the IPCC scenario A2 for 2011-2040, 2041-2070 and 2071-2100 periods. This work was done by using statistical and proportional downscaling techniques. For In estimating, Potential evapotranspiration (ETo) and effective rainfall (Pe) were calculated using Hargreaves – Samani equation and USDA method, respectively. Impact of water deficit on crop yield was estimated using the linear crop-water production function developed by FAO. Results showed that Net irrigation requirement (In) will increase when sowing date is moved toward winter season which would be of further limitations under climate change conditions. For the specific proposed sowing dates, the relative crop yield reduction (YD) was not significantly changed in the future compared to base period. If the sowing date is moved forward to winter season, YD will increase due to a higher evapotraspiration and lower available effective rainfall.
Keywords: Climate change, Net irrigation requirement, Wheat yield, General Circulation Model, CGCM3
Research Article
M. Akbari; E. Ranaee; S.H. Badiee
Abstract
Abstract
Desertification could cause reduction of the ecological and biological potential of land which may occur both naturally and artificially. Identifying and evaluating the effective factors in development of desertification is very important for better management of land. The aim of this research ...
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Abstract
Desertification could cause reduction of the ecological and biological potential of land which may occur both naturally and artificially. Identifying and evaluating the effective factors in development of desertification is very important for better management of land. The aim of this research is to evaluate the sensitive input parameters in the desertification condition by using of Artificial Neural Networks. The study area with 118658 hectars is located in south of Neishabour Township. During the past years, this area has been faced to increase in desertification rate due to some long consecutive periodic droughts, destruction of vegetation, converting of pasture lands to dry farms, water and wind erosion and unsuitable management of land use. After field studies preparation of aerial photos and satellite image, we prepared and analyzed the required layers in Geographic Information System. FAO-UNEP method (1984) was used for assess the Desertification rate. In this study vegetation condition, pasture condition, water and wind erosion and salinity has been defined and categorized as the factors in the status of desertification. After introducing the information to GIS, based on FAO-UNEP approach, the effective criteria were studied and map of desertification condition was achieved. The results showed that the desertification in northern parts of this area was serve which originated from the reduction of canopy, destruction of vegetation and water erosion and 62 and 30 percents of the whole studied area could be classified in moderate and slight conditions, respectively. Furthermore, to compare the results and quantifying the weight of input parameters, a mathematical model of artificial neural networks was used. The result showed that the effect of vegetation, wind erosion and water erosion could not be ignored and should be seriously considered. But salinity parameter is less effective than other factors in desertification and confirmed with FAO-UNEP method output. Analysis of different error criteria especially Mean Square Error with the value of 0.25 confirmed the accuracy of results.
Keywords: Desertification, FAO-UNEP, GIS, Artificial Neural Network, Neishabour Township
Research Article
S. Sanjari; M.H. Farpoor; M. Karimiam Eghbal; I. Esfandiarpour Borujeni
Abstract
Abstract
Geomorphology and soil genesis and its development are closely related. Besides, soil-landscape studies provide a better understanding of soil forming processes. The objectives of the present research include soil genesis studies, micromorphology and clay mineralogy of soils related to geomorphic ...
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Abstract
Geomorphology and soil genesis and its development are closely related. Besides, soil-landscape studies provide a better understanding of soil forming processes. The objectives of the present research include soil genesis studies, micromorphology and clay mineralogy of soils related to geomorphic surfaces in Jiroft area. Soil temperature and moisture regimes of the area are hyperthermic and aridic respectively. Alluvial fan, mantled pediment, intermediate surfaces, alluvial plain, and lowland landforms were identified. Each landform was divided into different surfaces due to geomorphic stability. One representative pedon was studied and sampled on each geomorphic surface. Routine physicochemical, clay mineralogy, and micromorphology analysis were performed on soil samples. The results showed that electrical conductivity, pH, and SAR contents increased from mantled pediments toward lowland positions. Besides, fine soil textures were found in downward positions. Chlorite, illite, palygorskite, smectite, and kaolinite clay minerals were found. Moving down toward alluvial plain, palygorskite stability decreased due to high water table, that is why smectite is the dominant clay mineral in alluvial plain. Source of palygorskite in mantled pediment, intermediate surfaces, and alluvial plain is inherited, pedogenic, and detrital respectively. Clay coating and infillings in Btn and Btk horizons of stable and unstable surfaces were investigated during thin section observations. Besides, calcite coating and infilling were found in Btk horizon at stable geomorphic surfaces. Results of the present research show that difference in soil characteristics is highly affected by geomorphology.
Keywords: Geomorphology, Palygorskite, Clay and calcite coating, Jiroft
