نشریه آب و خاک
سال بیست و هفتم شماره 6 (پیاپی 32، بهمن و اسفند 1392)

In arid and semiarid regions، controlled drainage is the next logical step towards improving water management in irrigated agriculture and reducing the environmental impacts of subsurface drainage flow. Controlled drainage has been practiced in humid areas for a long time. In this research a controlled drainage system in Khuzestan Province، Southwest Iran was tested as a strategy for continuous water table management with the benefits of optimizing water use and reducing unnecessary drainage and nitrogen losses from agricultural fields. To study the feasibility and performance of water table management، Field experiments were carried out on a 63. 41 ha with 3 treatments on the farms under subsurface drainage of Imam Khomeini''s sugarcane agro-industry. 3 treatments compared consisted of a free drainage treatment (FD) and tow controlled drainage treatment with water table controls set at 90 centimeter (CD90) and 70 centimeter (CD70) below the soil surface. Collected data during a sugarcane growing season included water table depth، drained volume، nitrate-nitrogen and ammonium-nitrogen concentration in the drainage water and groundwater. Controlled drainage had a significant hydrological and environmental effect during studding period. Compared with CD، the total drain outflow from CD70 and CD90 area were 62. 48 and 48. 98% less، respectively. Compared with CD، the total amounts of nitrate-nitrogen and ammonium-nitrogen in drain outflow were about 45 to 60 % and 50 to 65 % less، respectively. Nitrate-nitrogen and ammonium-nitrogen concentration in the both of drainage water and groundwater did not differ significantly in all of the treatment. These data suggest that controlled drainage can be applied at big scale in the Khuzestan Province with the most installed subsurface drainage in Iran، with advantages for water conservation and environment.

Organic phosphorus is the dominant part of soil phosphorus. Phytic acid and sodium Glycerophosphate are two different forms of soil organic phosphorus. Soil fungi play an important role in the conversion of these compounds into inorganic forms. Among the fungi، Aspergillus is one of the most effective organisms in hydrolysis of organic compounds. In order to study the ability of Aspergillus fungi on the hydrolysis of Phytic acid and sodium Glycerophosphate، an experiment was conducted as a completely randomized design with factorial arrangement and three replications. The first experimental factor include five fungi isolates (four Aspergillus isolates، Trichoderma harzianum and control) and the second factor include two different organic phosphorus compounds (Phytic acid and Sodium Glycerophosphate). All isolated were grown in PDB at 28 oC and rate of hydrolysis of inorganic phosphorus was determined after 14 days inoculation. In addition، acid and alkaline phosphatase activity and medium pH were measured. The results showed that Aspergillus isolates and Trichoderma harzianum mineralized organic phosphorus significantly (p)

The amount of available micronutrients such as zinc (Zn) is a primary concern in treated soils with sewage sludge. This study was performed to evaluate Zn availability (DTPA-TEA، Mehlich 1 and Mehlich 3) and its fractionation in soils before and after treated with sewage sludge (1% w/w) and after wheat plantation in greenhouse conditions. The results of this study showed that mean of Zn extracted by using chemical extractants after sewage sludge application increased significant (P0. 05). The results of fractionation showed that residual Zn، exchangeable Zn، Zn associated with organic matter، Zn associated with iron-manganese oxides، and Zn associated with carbonates increased 11، 26، 94، 172، and 279% respectively. The results of mean comparison showed that different between mean of Zn fractions (except Zn associated with iron-manganese oxides) before and after planting was significant (P)

Successful pressurized irrigation system accomplishment in a region is related to factors such as climatic conditions, water quality, topography condition, soil specifications, production variety and socio-economic factors. In this study a procedure has been expanded and introduced to scoring the effective factors in order to selection of pressurized irrigation system. In this procedure the degree of effectiveness are scored in 7 degrees by integer numbers of (-3) to (+3) on different factors. For preventing the equal effects of factors with different degrees of importance a coefficient as a weight of each factor has been taken into account. This coefficient on the base of special condition is determined by analytical hierarchy process. By analytical hierarchy process in corporation with geographical information system (GIS), this weight has been multiplied by the data layers. Final scores are provided by algebraic summation of each factor scores for each region. Really this score is the potential of each pressurized irrigation system. In this research potentiality of pressurized irrigation systems for 12165 hectares of down-stream lands of under study dam of Babakhan localized in Bijar of Kurdistan province is accessed and results are shown as maps with scores of each region of plan area for each pressurized irrigation systems. The results of this research show that out of 12165 hectares downstream lands of Babakhan dam, 4598 hectares (37%) were recognized proper to sprinkler irrigation and all of the investigated lands were proper to trickle irrigation. Also out of proper area for sprinkler irrigation, the portable riser sprinkler irrigation system has taken higher score and wheel move irrigation system ranked as second.

For optimal management of a catchment، the time and space downscaling of hydrological properties is essential. To achieve accurate energy and water budget equations in every time or space resolution، spatial and temporal downscaled information of water budget''s components are used. The fractal geometry is a branch of mathematics which has been utilized in discrete and periodic fields to generate data with different scales from observed data. In this research، the fractal interpolation functions were used for temporal downscaling of daily temperature data. The fractal dimension was used to express the rate of irregularities or fluctuations in the quatity. The fractal dimension of Mashhad daily temperature datasets for the period of 1992- 2007 was calculated. The mean of the fractal dimension was obtained 1. 54. Moreover، using the fractal interpolation functions and the midday temperature dataset with 15 days resolution، hourly temperature dataset has been estimated and compared with observed dataset. It was shown that despite the considerable time interval between two consecutive measurements (as 15 days)، the temperature time series with 3 hours resolution were obtained. The determination coefficient and the root mean square error of the model are 0. 77 and 7، respectively.

Sugarcane is one of the high consumption plants that has very high drainage coefficient. Irrigation frequency of Sugarcane in the maximum of consumption month is near 5 days and drainage systems often are removing drain water more than enough from the soil. This study was carried out to investigate the impact of controlled drainage on reduction of drainage coefficient and drainage volumes in three fields of Imam Khomeini sugarcane agro- industry. Two treatments were controlled drainage with water table controlling in 70 and 90 cm depth from soil surface (CD70، CD90) and the third one was free drainage (FD) treatment. According to the results، the CD treatments significantly reduced drainage coefficient during the study، compared to free drainage treatment. Average drainage coefficient in during the study in CD70، CD90 and FD treatments was 3، 4. 12 and 8. 98 mm/day respectively. Controlled drainage treatments (CD70، CD90) reduced drainage coefficient by 67% and 54% respectively، compared to free drainage treatment. CD70 treatment reduced drainage coefficient by 27%، compared CD90 treatment، too. The use of controlled drainage did not limited for plant growth and did not reduce sugarcane yield. Using of this method، in addition to the economic benefits will cause decreasing river pollution load and has a positive environmental impact.

In areas with limited water resources، one of the main goals of irrigation is to maximize the water per unit volume. In corn planting two major options for increasing of water productivity are plant density and growing pattern. In order to achieve the above goal in Corn” Karaj 700”، an study was conducted in strip split plots in frame of complete randomized block design with 3 replications in Khorasan Agricultural and Natural Resources Research Center for 3 years. Irrigation treatments were subsurface drip irrigation with 3 levels (50، 75 and 100 percent of full water requirement) in the vertical plots and plant density with 3 levels (65،75 and 85 thousands plants per hectare) in horizontal plots. In addition sub plots were including one and two rows planting pattern on 75 cm furrows. The results showed that irrigation water affected only on corn yield. The maximum yield in all three years was achieved by 100 percent of full water requirement treatment and the minimum yield was observed in 50 percent of full water requirement. The effect of subsurface drip irrigation on water consumption was not significant in the first year but it was significant in the last two years. The most water consumption was achieved by 100 percent of full water requirement treatment. Besides 3 levels of plant density and 2 planting types were not affected on water consumption. Plant height was affected by water quantity in 3 years furthermore this trait was affected by planting type in the second and third year. The maximum and the minimum of plant height were in 100 percent of full water requirement and 50 percent of of full water requirement respectively. The weight of 300 grains in different treatments was affected by planting type in the second year and in the third year this trait was affected by irrigation levels.

The objective of this study was to evaluate the long-term effects of mechanized sugarcan cultivation on some soil physical properties in several lands of Khozestan Sugarcane Agro-Industries. According to this، the experiment was carried out statistically as a randomized complete block design at 38 points in each of Deabal-Khazaei، Amir-Kabir، Karoon and Haft-Tapeh Agro-Industries with 5، 15، 40 and 50 years service. Measured soil variables included soil texture، electrical conductivity، sodium adsorption ratio، organic matter، equivalent calcium carbonate، acidity، bulk density (BD)، resistance of soil penetration (PR) at 16. 82-17. 96 moisture interval at two depths 0-40 and 40-80 cm and mean weight diameter (MWD) at soil surface and 40 cm depth. The results showed that BD and PR increased with numbers of years service and also، MWD increased caused by improvement soil organic matter content. The PR values increased with depth، which achieved to the greatest value at 55 to 80 depth interval. Also، results showned that the significant effect of number of years service on BD، PR and MWD، so that BD، PR and MWD with increasing the number of years service from 5 to 50 years were increased from 1. 57 to 1. 7 gr/cm3، 0. 98 to 1. 16 MPa and 0. 98 to 1. 76 mm at first depth and 1. 58 to 1. 79 gr/cm3 and 1. 29 to 2. 15 MPa at second depth، respectively. Whereas، non-significant change was found in MWD related to increase the number of years service at first depth.

Phosphorus is one of the main pollutants of agricultural surface drainage; that over standard doze of it cause eutrophication in surface water resource. This study investigates evaluation the ability of Semnan''s zeolite، that modified by hexadecyltrimethylammonium، to removal phosphorus under flow conditions in agricultural drainage. In this regard، after modifying natural zeolite، at first was absorption kinetics، adsorption isotherms، affecting of pH and temperature experiments on phosphorus removal conducted by modified zeolite in laboratory scale. The experiments were done in 3-5 mm size of zeolite for investigating effect of zeolite size on phosphorus removal. In order to assess the flow conditions on phosphorus removal physical model of agricultural drainage and the modified zeolite filter ponds were constructed in length of 2، 3 and 5 cm. The both discharge 0. 05 and 0. 1 lit/s were applied in drainage and changes of phosphorus concentrations were measured at various times after passing through the filter ponds. The sorption kinetic experiments showed maximum phosphorus removal by modified zeolite occurred in the first 2 hours. Moreover، percent phosphorus removal with increasing the pH from 3 to 8 decreased and increased from 8 to 12. Also percent removal with increasing temperature in the range of 17 to 30 °C decreased. The results showed Langmuir isotherm had good agreement for explan phosphorus removal by modified zeolite. The results of physical model showed that higher percent phosphorus removal occurred in higher discharge and lower length of filter pond due to more contact drain water with the modified zeolite.

Detection of rainfall characteristics in arid and semi-arid regions such as northeast of Iran has a critical role in any adaptation and mitigation plan to drought. The main goal of this study was to determine the rainy season starting date and daily rainfall threshold by using Rainfall Uncertainty Evaluation Model. The Starting Analysis Date (SAD) characterize the beginning of a new rainy season in a given region، whereas، the Rainy Season Beginning Date and the Rainy Season Ending Date are used to determine the Rainy Season Length. In this study، seventeen locations in northeast of Iran with available long daily rainfall data (24 to 48 years) were selected. Our results indicated three annual courses of rainy season، 12 locations showed a uni-model annual course with shorter values in summer (A courses)، 4 locations indicated uni-model with shorter rainy season length across April and March (B courses) and only 1 location showed bi-model annual course (C courses). These classifications were confirmed by multivariate statistical methods analysis. SAD was determined by differences between shortest median RSL and the shortest median RSL of the first day of each month. According to this approach SAD values for different classes determined as: July 1st in (A) region، March 1st in (B) region and February 1st in (C) region. Appropriate daily rainfall threshold was 1. 0 mm for only 3 locations، and the highest value of this index obtained in Torbat-j location (2. 2 mm)، therefore 1. 0 mm value which traditionally is in use as daily rainfall threshold need to be revised.

Prediction of precise forage production and proper management strategies requires identifying key climatic factors in different regions. The objective of this research is to compare forage production in different region based on climatic factors and drought indices. The study sites include Arak، Roudshore، Baghic، and Gharahso in Central and Qom provinces. Climatic factors and drought indices include precipitation، temperature، evapotranspiration، standardized precipitation index (SPI)، and Reconnaissance Drought Index (RDI). For each climatic variable/or indices، 33 time periods of 1، 2، 3، 4، 6، and 9-month were specified. We have used Principle Component Analysis to decline the number of variables and then، the appropriate time periods were selected. By using stepwise and best subset، the relationship between forage production and each of the climate factors and indices was modeled. To select model، assessment statistics of R، MBE، RMSE، MARE، and IPE were used. Finally، to predict forage production in Roudshore، Baghic، and Gharahso sites، models based on evapotranspiration (RMSE=7. 7، r=0. 99)، RDI (RMSE=3. 1، r=0. 99) and precipitation (RMSE=4. 0، r=0. 99) were selected respectively. The best model was based on the combinations of climatic factors and drought indices (RMSE=0. 2، r=0. 99) for Arak. In general، the relation between forage production and drought condition based on RDI is stronger than its relationship with precipitation and temperature. As we have used precipitation and evapotranspiration simultaneously in RDI، so this index is more precise than SPI.

In order to assess uptake potential of Cd an Zn by Gladiola، Narcissus and Tulip، the greenhouse study was performed in contamination soils as factorial arrangement based on the complete randomized design with different levels of pollution (A as higher pollutant، B as lower pollutant and C as no pollutant) and different flowers (Gladiola، Narcissus and Tulip) with four replicates in faculty of agriculture، Bu-Ali Sina University. The result showed that with increasing heavy metals concentration in soils، dry matters of Gladiola and Tulip were decreased، compared with the control; however there was no change for dry matter in Narcissus. The accumulation of Cd and Zn by flowers increased with increasing soil pollution. The Cd concentration was higher (3. 48 mg/kg averagely) in aerial parts of plant harvested from the A level treated soils which was significantly difference with B and C levels treated soil. There was no difference between the B and C level treated significantly. The Zn concentration in the aerial parts of plant was in the order of A، B and C level treated soils (in average 26. 03، 17. 46 and 13. 99 mg/kg respectively). The Cd uptake was equal in all parts of Gladiola، Narcissus and Tulip. The Zn concentration was higher in the aerial parts of Tulip than Gladiola and Narcissus that of underground was equal. The accumulation and translocation Indices of Cd was not affected by increased soil Cd concentration significantly. With increased Zn concentration in soil، accumulation index decreased while translocation index was not changed significantly. The translocation and accumulation index of Cd and Zn was similar for flowers. Thus accumulation of Cd and Zn in saleable parts of Gladiola، Narcissus and Tulip led to clean up the contaminated soils.

Since measuring the flow discharge is difficult during a flood event in a hydrometry station، the estimated Stage–discharge relationship of non-flood conditions is extrapolated for flood conditions. Hence the results might show underestimated values. Indeed during the flood bed form is developed and flow resistance changes. In order to establish a more accurate stage–discharge relation، it is important to apply a method which considers (or takes into account) the bed form resistance. This research tries to determine the best method for developing such relationship in hydrometry stations located on the Qarasu river basin such as: Ghorbaghestan، Doabmereg، Khersabad، Hosseinabad and Sarasiab. To reach this aim، the required data (e. g. river cross section، bed material gradation) were measured for these hydrometry stations and methods of Einstein–Barbarossa، Shen، White، Engelund، Brownlie and VanRijn are used to obtain the stage–discharge relationship. A computer program was developed to estimate stage-discharge relation based on afore mentioned methods. Different statistical tests were accomplished to compare estimated and observed discharges. The results in Ghorbaghestan and Hosseinabad stations showed that the regression slope between the measures and calculated values by the Einstein–Barbarossa’s method respectively 1. 029 and 1. 182. by using Shen’s method in Doabmereg، Khersabad and Sarasiab stations respectively 1. 08، 1. 054 and 0. 926 While regression slope in other methods is greater than 1، also AME and RMSE is much less than other methods on the appropriate methods. In hydrometry stations with coarse bed material Einstein–Barbarossa’s method is more convenient to estimate stage-discharge relation in comparison with other methods. Also for hydrometry stations with fine-grained bed material Shen’s method was found a reasonable method to estimate stage-discharge relation.

Changes in temperature and precipitation patterns have serious impacts on the quantity and quality of water resources، especially in arid regions such Iran. In recent years، frequent droughts have threatened the water resources in Iran. Because of the increasing demand for water، studying the impacts of climate change on water resources is necessary. In this study، the impacts of climate changes on run-off in Ajichay watershed، located in East Azerbaijn were considered. To predict the climate change based on the General Circulation Models (GCM)، the LARS-WG tool for downscaling was used. By using LARS-WG، climate change in Ajichay watershed by applying HADCM3 model and three emission scenarios، A1B، A2 and B1 in 2055 horizon was investigated. The results show a rise in temperature and reduction in precipitation. In the other part of the research، for simulationofthe impacts of climate change on watershed run-off، Gene Expression Programming (GEP) was used. The results indicated that significant reduction in run-off. With regarding the results of this research، for adaptation with climate change، it is necessary to consider suitable management action in this watershed.

During the last decades، urbanization expansion and industrial activities in large cities have led to remarkable changes in weather and local climate. Nowadays، analysis of meteorology data and also using them in programming the development of habitation centers are of importance and climate situation affects people’s comfort. In fact، by recognition of city’s climate conditions in different months of the year and analysis of meteorology data، construction of climate comfort is possible. In this study، the monthly data of 4 climate factors (temperature average، minimum temperature، maximum temperature & relative humidity) from Aabadan’s meteorology station over 60 years (1330-1389) have been used. Using regression process، incongruity of data was evaluated and data’s homogeneity was studied by sequences’ examination. Then، using Mahani comfortable climate model، suitable months for convenience of human physiology in 6 ten-year periods were determined. Then، using Box–Jenkins models time series for 3 factors of climate، minimum temperature، maximum temperature and relative humidity is studied and the best model is fitted. Then، using suggested models، the next 10 years of any climate factor was predicted and the next years were studied from the viewpoint of comfortable climate using Mahani model. The results of this study indicated that based on Akaike criterion، the best Box–Jenkins model for minimum temperature is ARIMA (1،1،1) × (0،1،2) ¹² model، for maximum temperature is ARIMA (0،1،2) × (0،1،1) ¹² model and for relative humidity is ARIMA (1،1،1) × (0،1،1) ¹² model. As for nightly comfortable climate، temperature has increased in Bahman، Esfand، Farvardin and Ordibehesht months. Temperature has decreased in Mordad، Shahrivar an Mehr months. As for daily convenience climate، temperature has increased in Dey، Bahman، Aazar and Esfand months، and temperature has decreased in Mehr month.

Lake Urmia is faced with problematic drawdown trend in the recent years that climate change can exacerbate this phenomena. This research work applies HadCM3 climate change data (scenarios A2 and B2) for the period of 2010-39 to evaluate changes in temperature and rainfall of the basin. To downscale these data a new approach is used، which is a combination of SDSM model and TOPSIS approach. Furthermore، the climate change data was introduces to the Soil and Water Assessment Tools model (SWAT) that was calibrated using local data and information to evaluate future changes in the basin’s runoff. Of course at this stage، only the Simineh Rud subbasin as one of the basin’s main subbasin was investigated. The results showed that climate change will reduce monthly rainfalls up to 40% and increase the temperatures up to 2 °C. Also، the basin’s runoffs will face with reduction of about 25%. Consequently، the inflows to lake may decrease about 30%. In general، the results of this research work emphasize on more attentions to the problems of the lake that will be booster under climate change condition

Assessing the level of reservoir’s Eutrophication has been regarded as one of the main issues in the water quality management by managers and policy makers. Estimating the eutrophication level is not possible by a determined method and complete certainty with respect to the high complexity of this phenomenon. Fuzzy theory is an approach by which the lack of transparency and uncertainty can be determined between the levels of eutrophication. In this study، Entropy- based Fuzzy Eutrophication Index (EFEI) and Trophic State index (TSI) were used for the trophic level classification of the Ilam reservoir epilimnion and hypolimnion during a year. These indexes were weighted with two scenarios based on the chlorophyll a، total phosphorus and oxygen saturation parameters. In the first scenario، the relative weights of indexes were calculated by the combination of entropy- based fuzzy approach and analytical hierarchy process. In second scenario، equal weight was considered for all parameters. The results showed that based on both scenarios and in most months of the year the trophic level of the epilimnion was oligotrophic with suitable certainty and it was only mesotrophic in July and August. In the hypolimnion، the trophic level was similar to the epilimnion، but uncertainties have been increased.

Predicting behavior and the geometry of the channels and alluvial rivers in which the erosion and sediment transport are in equilibrium is one of the most important topics in river engineering. Various researchers have proposed empirical equations to estimate stable river width (W). Empirical equations were tested with a comprehensive available data set consisting of 1644 points collected from 29 stable rivers. Moreover، these equations are compared with new model in this article for estimating W. The data set covers a wide range of flow conditions، river geometry، and bed sediments. These data set is classified in two groups (W)

In order to investigate impactes of furrow firming on furrow irrigation performance، a field experiment was conducted during Sugarbeet growing season in Nagadeh. Four furrow irrigation treatment of furrow firming includes B1: furrow firming with once roller، B2: furrow firming with twice roller، B3: furrow firming with thrice roller and B0: without furrow firming were considered to collect field data for 1388 period and all evaluation parameters were collected. The surface irrigation model: WinSRFR، was calibrated and evaluated by using field measurements data. Furrow Infiltration and Roughness parameters، was calibrated by multilevel optimization method. The maximum relative error for estimation of advance and recession times and runoff were obtained 2. 1، 4. 7 and 4. 5%، respectively. For 13 irrigation events assessment، application efficiency of B0، B1، B2 and B3 were obtained 50. 03، 55. 77، 60. 22 and 62. 31%، respectively. So as to increase irrigation performance، optimal combinations of cutoff time and inflow rate were extracted for all irrigation events and treatments. Under B3 furrow firming، the mean water productivity increased about 17. 8% compared with without furrow firming. Beside with assumption of optimal cutoff time and inflow rate، water productivity is increasable about 27%.