Journal of Water and Soil Conservation
Year:2019 | Volume:25 | Issue:6 |Papers Count:25

Background and Objectives: Nowadays, in addition to increase in the population growth, decrease in precipitation and surface flows in arid and semi-arid regions of the world, has caused to increase the extraction of groundwater resources and therefore many problems in this valuable and non-renewable resources. In this regard, assessing, monitoring and prediction of the groundwater resources behavior is significant. In this study, a developed numerical simulation model with finite difference solution using MATLAB was applied to evaluate the groundwater elevation changes in a real case. Materials and Methods: The study area is the Namdan aquifer located in the Tashk-Bakhtegan basin, Fars province, Iran. The transient finite difference model was developed to assess the groundwater elevation changes. For setting up the model, the study area zoned manually considering the various factors and finally 50 cells were considered. In addition to the groundwater flow interactions between cells, the interactions between boundary cells and inflows and outflows boundaries took account into the modeling. The recharge parameters were calibrated using try and error method while the hydraulic conductivities were calibrated using an optimization problem with an objective function of minimizing the residual sum of squares of water table prediction and observation (a period of 7 years) using an evolutionary ant colony optimization tool and R􀬶 =0. 93 obtained. Furthermore, the calibrated model verified for a period of 3 years. Results: The aquifers condition was assessed in transient condition for a period of 30 years, under 7 various scenarios which have been compiled from climate, utilization, crop pattern and the aquifer restoration plan of Iran indexes. By a decrease of 10% in the precipitation and an increase of 20% in the extractions, the groundwater elevation will drop by 0. 9 meter and 6. 1 meter, respectively. Changing the crop pattern from wheat to barley, which consumes less water, causes 4. 4 meters rising in the groundwater elevation. In the removing unlicensed wells scenario, the annual water level rising will be 0. 45 meter in average. Conclusion: The groundwater elevation has been faced with the most changes in the scenario of removing unlicensed wells in all over the study area compared to other scenarios and at the end of simulation period, it would be predicted that the groundwater elevation will increase about 19. 6 m. This shows the necessity of paying attention to determining unlicensed wells condition in the aquifer restoration plan more than ever.

Background and Objectives: Due to the limited surface water resources and reservoir capacity of dams, scientific management and optimal utilization policy of reservoirs is essential and vital in meeting the water requirements. Also, considering the importance and utilization of water resources and the optimal allocation of this scarce resource among different uses in the Sistan region, it seems necessary to establish a plan to achieve this goal. In the studied area and in the country, so far, an investigation into the optimal allocation of water with the application of advanced PSO algorithm for optimization of Chah-Nime reservoirs has not been used. Therefore, in the present study, the optimal allocation of water resources in the Chah-Nimeh reservoirs have been investigated under three management scenarios (scenario of stabilization of micro-organisms, agricultural development and transfer of second drinking water pipeline from Chah-Nime reservoirs to the district of Zahedan) using the metamorphic technique of congestion Particles (PSO). Materials and Methods: Particle Swarm Algorithm is one of the most widely used metaalgorithms, which is used in optimization problems. In the mass optimization algorithm of particles, there are organisms called particle and are spilled in the search space of a function that is intended to minimize (or optimize) its value. Each particle calculates the value of the target function in the position of the space in which it is located. In this research, the algorithm was used to allocate optimal water resources. The objective function in this research is to optimize and maximize the amount of water supply. Also, the constraints are related to the objective function, the systematic constraints, the constraints and limitations of the algorithm and the constraints and limitations of the reservoirs in the region. Results: According to the results, the optimum release rate in 1995 (first year) was 39. 35 million cubic meters, with the demand of 98. 31 million cubic meters, which did not meet the required amount of 72. 91 million cubic meters. The comparison of the last four years shows that in the year 29, lack of supply is less than the next three years. The scenario of stabilization of the microstats in the study area was considered as a serious project. The results of this scenario showed that the application of the used algorithm can properly optimize the allocation of water resources. According to the results, it is suggested that ultra-modern modeling can achieve more optimal allocation with the minimum error in the target function. Therefore, these multifunctional algorithms should be considered in managing the optimal allocation of resources and used in future planning and policy making.

Background and Objectives: Regards of water scarcity, inappropriate distribution of precipitation, implementation and development of projects in water resource fields such as dam construction and inter-basin water convenience is unavoidable. For prevention of long-term negative environmental impacts of such projects and for water allocation acts, it is necessary to study hydrological and ecological demands of river as an "environmental water demand". The "environmental water demand" usually is defined as a set of discharges which are determined by the magnitudes, frequencies, occurrences and given flows, but the employed methods in this research calculate environmental flows in the form of mean annual runoff (MAR). These flows which provide appropriate conditions for conservation of aquatic life and ecosystem processes for sustainability goal, are called "environmental flows". This article aimed to study the "environmental demand" estimation for Mahabad-Chai River. Materials and Methods: Mahabad-Chai sub basin is located on southwest of Lake Urmia; and considering its extent, it is the fourth largest sub-basin of Lake Urmia Watershed. Its geographic area ranges from 44˚ 45΄ E to 45˚ 56΄ E and 36˚ 22΄ N to 37˚ 10΄ N and is composed of two main branches “ BYTAS & KOTER” . The ecological river demand was estimated and compared with four hydrological methods (Tenant, Tessman, FDC-shifting and DRM), then suitable method was introduced. Results: The ecological demand of Mahabad-Chai river is estimated and compared by four hydrological methods, FDC-shifting method biological class C, because of considering ecological specifications of the river, was chosen and the environmental demand of Mahabad-Chai River was estimated to 0. 35 cms in BYTAS station and 1. 17 cms in KOTER station. The annually average flow was 1. 73 and 6. 17 cms in BYTAS and KOTER hydrometric station respectively. Conclusion: Based on the results, the suggested flow of FDC-shifting method at C class is recommended as minimum environmental flow for Mahabad-Chai River, because this method needs the less data, doing early and rapid assessment in data and simulating current hydrological conditions by considering desirable ecological conditions, whereas other methods can’ t do this action. Moderated class C (relatively modified) consider about %20 MAR to %30 MAR as environmental flow, that in this condition basic function of ecosystem has not changed and more species is survived. Also moderated class C has good match with regime of flow at several months and is acceptable in area in terms of managerial, agricultural uses, drinking and etc. The suggested method in this research is not the ultimate solution for environmental problems of Mahabad-Chai River. Lack of comprehensive required ecological information at river’ s ecosystem studies, cause to estimating eco-hydrology by less coefficient of confidence.

Background and Objectives: The adsorption is one of the most important chemical processes affecting the mobility and availability of Zinc (Zn) in the soils. Moreover, the presence of cations in the solution may affect Zn adsorption. Adsorption isotherms were used to determine the characteristics of Zn adsorption. The adsorption isotherms describe relation between adsorbed metal on sorbent and its concentration in equilibrated solution at a constant temperature. The calcium‚ sodium, potassium and ammonium are the important cations in soil. In this study, the effect of the calcium‚ sodium, potassium and ammonium on the Zn adsorption in 5 calcareous soils in Chaharmahal va-Bakhtiari was investigated. Materials and Methods: An experiment was performed using completely randomized design to determine the characteristics of adsorption isotherms of Zn in the studied soils and in the presence of different electrolytes. At first, 2 grams of each soil (in 3 replicates) placed into centrifuge tubes, then 20 ml of solution ZnSO4 contains 25, 50, 75, 100, 150 and 200 mg / l of Zn in Ca(NO3)2, NaNO3, KNO3 and NH4NO3 electrolytes (at a concentration of 50 mM) were added to the tubes and the samples were shaken with electric shaking apparatus for 24 hours and then were centrifuged (3000 rpm). The soil solution was separated and concentration of Zn in all extractants (in equilibrium) was determined using atomic absorption spectrophotometer (GBC model, 932). In the following, the concentration of adsorbed Zn was determined from the difference between initial and final concentration (equilibrium concentration). Then the Langmuir, Freundlich and Linear equations were fitted to the data. Results: The results showed that concentration of adsorbed Zn in the all soils and all electrolytes increased by increasing Zn concentrations in the equilibrium solution. Amount of adsorbed Zn in the presence of Ca2+ was lower than the presence of Na+, NH4 + and K+. The Freundlich and Langmuir equations have the highest determination coefficient (R2) and the lowest standard error of estimate (SE). Therefore, these equations were able to describe the characteristics of Zn adsorption. The result of mean comparison showed that the maximum adsorption capacity (b in Langmuir equation) and adsorption intensity (n in Freundlich equation) were highest in the solution contains sodium, calcium, potassium and ammonium, respectively. The coefficient related to the binding energy (k in Langmuir equation) and maximum buffering capacity (MBC in Langmuir equation) were highest n the solution containing potassium, ammonium, sodium and calcium, respectively. The highest distribution coefficient was in solutions containing sodium, potassium, ammonium and calcium, respectively. Therefore, the highest and lowest affinity of Zn to adsorb onto soil solid phase was in the presence of sodium and calcium, respectively. Conclusion: The results of this study illustrated that sodium can decrease mobility of Zn in the calcareous soils more than the other cations.

Background and Objectives: One of the ways to express physical behavior of soil is to describe of the soil structure. Since soil physical quality could not be measured directly, therefore, the special properties defined as indicators, are used to express the soil physical quality. Of different indicators, including S-index is used to express the physical quality of the soil which is the slope of the soil water retention curve at inflection point. It seems that little research has been done on the effect of landuse on the S-index, therefore, the purpose of this study was to compare the results of S-index in three different soil water characteristic curve models (Van Genuchten, Brooks-Corey and Grant-Groenevelt models) in 5 different land uses in Jiroft city. Materials and Methods: For this reason, 350 disturbed and 350 undisturbed soil samples from different landuse (citrus, palm, arable, forest and combinatory) were collected. Some of the physical and chemical features of the soil, including sand, silt and clay percentage, the electronic conductivity at saturation, Bulk Density, the percentage of the total porosity and the percentage of the Organic Matter were measured. Also, the amount of the soil moisture in suctions 0, 10, 30, 50, 100, 300, 500, 1000 and 1500 KPa was determined using pressure plates device. Results: The results showed that in the study region the best physical quality of the soil was seen in palm land use. All landuses, except forest, had proper physical quality. High value of S index in citrus, palm and arable land uses can indicate better soil management at the start of farming. In combinatory land use, due to Simultaneous cropping of alfalfa and palm, alfalfa causes more organic matter to be returned to the soil and as a result, the soil structure improves, which is displayed at high value of S index. In general, The S index was higher in landuses where the soil had better structure or management operations were improved. Conclusion: In general, despite the slight differences in citrus, palm and cultivate landuses, palm landuse had a higher mean of S index. So that their values in Van Genuchten, Brooks-Corey and Grant-Groenevelt models were 0. 06, 0. 06 and 0. 04 respectively. The results of this study showed that the Van Genuchten model accuracy was better in estimating and evaluating the soil quality due to the greater distinction between the soils with close physical quality. Because the fitting of Soil water characteristic curve had a higher R2 (R2=0. 92). However, due to low differences with two other models, in particular the Brooks and Corey model (R2=0. 87), It seems that, a suitable model for assessing soil quality in different landuses varies. Therefore, it is imperative that this index and other indicators of soil physical quality assessment in different climates are more explored.

Background and Objectives: Industrial wastewater and water contaminated chemicals are released into the environment and, as a result, contamination of the soil is adsorbed and contaminated with limited resources, cause production of harmful and unhealthy products for health. One of the best ways to remove organic pollutants from contaminated water is by adsorption. The purpose of this study is to remove phenol pigment from aqueous solutions by magnetic nanoparticles. Materials and Methods: Magnetite nanoparticles were synthesized by the sedimentation method and simultaneously reconstructed Fe+3 / Fe+2 ions with a ratio of 2 to 1 with NaOH in aqueous solution under nitrogen atmosphere and identified by IR, SEM and XRD methods. To determine the maximum phenol red absorption wavelength concentration, the UV-VIS spectrophotometer was evaluated in the wavelength range of 400 to 800 nm, with a maximum phenol-red wavelength of 431 nm. The phenol red adsorption on Fe3O4 nanoparticles was evaluated in a discontinuous medium. The parameters studied in this study included the initial values of nanoparticles (0. 005, 0. 01, 0. 015 and 0. 02 g), phenol red primary concentrations (5, 10, 20 and 30 mg/l), primary pH (1, 4, 7, 9 and 12), contact time (5 to 40 minutes) and nano-adsorbent desorption process. Langmuir two-parameter adsorption isotherm models, Freundlich and Tempkin were studied. Experimental comparisons were studied with pseudo-first kinetic models, pseudo-second-order and inter-particle influences. The effect of temperature on the adsorption process was investigated by investigating the thermodynamic constants of the adsorption process including Gibbs free energy (Δ G0), change in entropy (Δ S0) and enthalpy change (Δ H0) at temperatures of 293, 300, 305 and 310 K. Results: By increasing and decreasing pH from 7, the phenol red removal rate was increased. Increasing the phenol red adsorption in low and high pHs relative to neutral pH is due to the conversion of pollutant to ion, which increases the adsorption of phenol red contamination on nano-adsorbent. The adsorption takes after 30 minutes to equilibrium. The maximum adsorption capacity occurs at 30 mg/L of the contaminant in the presence of 0. 01 mg/l of the adsorbent and at 20 ° C and at pH= 7. Due to the process heat-up, the increase in temperature increases the amount of adsorption. It is observed that when temperature increases the amount of adsorption will increase. The Freundlich isotherm is in better agreement with experimental data. The pseudo-second-order model with a correlation coefficient of 0. 9999 and a speed constant of 0. 0202 is the best kinetic model describing the adsorption process. The values of the thermodynamic constants Δ H0 and Δ S0 are 278. 89 kJ / mol and 288. 38 j / k. mol, respectively that indicate that the adsorption process is endothermic and an increase in ambient temperature at the solid-liquid interface during absorption. The negative Δ G0 indicates that the adsorption process is spontaneous. Conclusion: Magnetite nano-adsorbent can be used as an appropriate adsorbent to remove phenolic contaminants from polluted aqueous solutions and industrial wastewater before releasing into the environment.

Background and Objectives: The agricultural sector plays a vital role in the national economy and food production in Iran. In the meantime, due to the country's particular climate and the disproportionate distribution of time and place of precipitation, water cultivation is the main driver of food production. In arid areas such as Khuzestan province, nearly one hundred percent of agricultural production comes from water cultivation. According to the Research Center of the Iran Parliament, the population of Iran is projected to reach 100 million by 1410, which will require more than 150 billion cubic meters of water per year to meet the population's nutritional needs, based on approximately 2600 kilos calories per day. This amount was not available in the country's water basket, so resource management should be used to increase water productivity. In at globalizing world, where problems increase with the effect of warming and climate changes, it seems that decrease in usable freshwater bodies will pose a serious problem. This study intends to investigate climate change impacts on evapotranspiration (ET) of agricultural crop in Khouzestan province in future periods. The importance and urgency of the subject and the limited research done in this regard, the local and regional effects of climate fluctuations on the evapotranspiration of agricultural products are of particular importance. These changes are of great importance, especially in fertile and agricultural areas such as Khuzestan. Materials and Methods: In this research, the effect of climate change on precipitation and evapotranspiration of agricultural products in future periods was investigated. The CanESM2 atmospheric general circulation model (GCM) data under two RCP scenarios (IPCC-AR5) were used in Khuzestan province. To determine the feasibility of future periods meteorological data production of SDSM model, calibration and verification was performed for the base periods (1990-2005). Minimum and maximum temperature and precipitation estimated by SDSM method by CanESM2 data in three future periods: 2030s, 2060s and 2090s and compared with historical data. The strategic agricultural products such as wheat, barley, rice, corn and sugar cane were selected for this study. Potential evapotranspiration of these products were used during the cultivation period. According to the fifth report of the Intergovernmental Panel on Climate Change (IPCC) using CanESM2 model under RCP scenarios, meteorological data in the upcoming periods were simulated, the potential evapotranspiration of periods were calculated with information generated in the upcoming periods. Results: The results showed that the average temperature in all selected stations and in all scenarios about 4 ° C and this increase is higher in RCP8. 5 scenario than RCP4. 5 scenario. The average precipitation reduce in 2060s and 2090s. The ET for all agricultural crops has increasing trend, but the increase for rice and corn is expected to be higher than others over the period 2060 and 2090. Conclusion: It can be concluded that studied crop ET will increase in future periods, therefore we should consider that there will be lack of water and less crop production in Khouzestan province. We should change our cultivation periods and cultivate more effective crops in order to increase water efficiency and decrease potential evapotranspiration in some area of Khouzestan province.

Background and Objectives: Managers and policy makers, to take appropriate managerial strategies, including product price and products' market on import and export need information about performance of agricultural products at different scales, but estimation of product yield amount regarding the lack of required information is always difficult and costly. The most appropriate way is satellite data and remote sensing technique. The present study aims at estimating the sugarcane product yield using Landsat 8 satellite images. Materials and Methods: In this research, a hybrid model was used to estimate the product yield. This hybrid model includes many models to calculate the absorbed photosynthetic active radiation, the Stanford model to determine the light use efficiency and SEBAL model to describe spatial-temporal variations of the earth's surface. The product yield map of the implementation of this model on 2013 using 10 Landsat 8 satellite images has been achieved. In SEBAL model, all energy balance components including net radiation, soil heat flux, tangible heat flux from satellite imagery was calculated and finally the evaporation fraction was calculated based on the energy balance equation. To estimate the produced dry material according to the date and number of images, photosynthetic active radiation in 10 time periods has been calculated. Each image represents an interval time period. In this research, all components of this hybrid model for all images in the time period of the main course of sugarcane production growth was calculated and finally, the product yield map was prepared for this area. Results: The average yield of sugarcane during growth period was estimated in 65 tons per hectare. Estimated yield with this hybrid model, showed good correlation and good distribution with the actual yield of farms (􀜴 􀬶 = 0. 8339). Then, the effect of age and varieties on the accuracy of the model in the sugarcane performance estimation was studied. It was found that, among different statistics, the calculated yield values in cultivated farms of CP57-614 due to its precociousness and better alignment with the latest image has higher correlation with actual amounts of yield. Also it has been seen that with increasing the age of sugarcane from the planting to R4, the yield will decrease and will have lower estimated yield, correlation and distribution comparing with actual sugarcane yield and the correlation is reduced to 0. 51. Conclusion: The results of evaluation of product performance data and cultivated varieties indicated that the sugarcane product yield is higher in the 614-CP57 than in the 1062-CP69 and it also shows a better match with the presented model. Also it was observed that with increasing different ages of sugarcane from planting to R4, the performance was decreased and had lower estimated yield, correlation and distribution than the actual yield of sugarcane and error rates will increase.

Background and Objectives: The concept of ‘ desertification’ is related to loss of ecosystem services because of human disturbances and climatic variations in dry regions. Desertification based on its driver and geographical condition can change ecosystem downward in stable statue. Desertification control needs to identify its drivers and causes. Desertification drivers can be categorized in biophysical, social, economic, political and managerial groups. In this paper, some of the disturbances caused by human activities that have been linked to the knowledge and culture of the rural people and which underlie the current state of degradation and desertification have been evaluated as a desertification social driver. Materials and Methods: In order to carry out this research, a list of social driving forces has been prepared through the related scientific resources review, a questionnaire and a specialized group of related experts in two phases of the Delphi method. Then, the candidate factors were grouped into 6 criteria. At last, by using the questionnaire, whose validity and reliability were confirmed, was judged by experts. Finally, it has been ranked by statistical methods and the Analytical Hierarchy Process (AHP). Results: The results of statistical analysis using SPSS19 software showed that the most important criteria of socio-cultural effective on desertification and land degradation were 20. 49, 19. 32, 17. 36, 16. 76, 13. 12, Percentages are as follows: Social networks weakness, disproportionate historical and cultural habits, population migration, the weakness of knowledge and education, the loss of social values and land ownership issues respectively. Using a hierarchical analysis method (AHP), it was found that among the 38 candidate candidates, 18 factors were more effective. Also, the most important factors affecting land degradation and desertification are as follows: the lack of a system for using Hamoun wetland products and services, farrow land cultivation, traditional farming, untrusting to experts knowledge, the preference for crop cultivation and lack of utilization Indigenous knowledge respectively. Conclusion: If the goal of stopping desertification or reversing it is the need for comprehensive review, more effort is needed to bring the views and cooperation of all stakeholders, including stakeholders, especially beneficiaries. Knowledge sharing trust building and cooperation in implementing projects can be beneficial for the government and the people, Corrective policies in such region with high rate of land degradation and desertification can be achieved through Understanding the causes and factors of this phenomenon.

Background and Objectives: Soil pollution by heavy metals in the world, especially in countries that require soil to produce food, has become a serious concern. In the context of environmental risk assessment, earthworms are an important component of soil and ecologically considered as a biochemical indicator (bio Index) for soil health and quality. Earthworms are part of the food chain and the soil decomposition cycle, whose growth characteristics i negatively affected by soil contamination. Due to the sensitivity of dirt worms to contamination, they can be used as an indicator of contaminated soil. This study was carried out in order to investigate the effect of contact time and soil sampling location on the growth traits of earthworms in contaminated soils. Materials and Methods: The study was conducted on a contaminated soil that was sampled from the Ahangaran mine and its surrounding land, located at the 26 kilometer far from Malayer to Arak, in the Hamedan province, which lies between longitudes and latitudes 44° 59' 44'' and 34° 10' 20'', respectively. A factorial experiment was conducted in a completely randomized design with three replications. Animal fertilizers were used as nutrition for soil worms. In this experiment, 12 earthworms with an average weight of 0. 3-0. 6 mg were selected for each soil sample and during the experiment, no food was added to the dishes. Then, the worms were exposed to soil contamination in seven different time intervals of 3, 7, 14, 21, 28, 32 and 42 days. The viability, weight, cocoon production and reproduction were investigated by hand counting in unit of the substrate weight. Results: The results of analysis of variance showed that lead and cadmium contaminated soils can somewhat affect growth parameters of Eisenia foetida. The number of earthworms decreased with time, so that on the 3rd and 7th days, the highest percentage of earthworms (94. 52%) and the lowest percentage (73. 180%) of earthworms were observed on day 42 with significant difference, which could be due to depletion of food source for earthworms over time. The highest amount of cocoon produced in days 28 and 32 was observed with significant difference when compared with other days. The significantly lowest amount of cocoon produced was observed on day 42, probably due to the completion of the cocoon cycle and the conversion of the cocoon to the lavar. Despite the high concentrations of lead and cadmium in point S3, the highest percentage of survival, number of cocoons and larvae (reproduction) of earthworms was observed, which could be due to the high resistance of earthworms to the toxic effects of cadmium and lead because of its detoxification by metallothionein proteins in dorsal canals. Conclusion: Generally, the decline in population, weight and cocoon production were more pronounced along with increase of the earthworms exposure time. However, when earthworms were fed to heavy metals such as lead and cadmium with animal fertilizer, population decline, weight and number of produced cocoons were less, so increased cocoons number and reproduction were occurred at the end of the trial. Due to the sensitivity of growth traits of earthworms, they can be used as indicators of soil contamination.

Background and Objectives: Evaluation of the effects of land-use change on water resources is an important component of hydrological modeling. Land use change is an important characteristic that influences erosion, evaporation, transpiration and runoff. Nowadays, preparing land use maps via satellite data and quantitative methods is very common in remote sensing studies. These techniques were widely used by scientists in the past two decades. The main aim of this study is to investigate the potential effects of land use change on surface runoff production using SWAT model. Materials and Methods: The study area, namely Behesht Abad, located in the North and North East of Karoon watershed, Chaharmahal and Bakhtiari Province, Ardel Township. For this study, land use maps were created for the period of 1987-2013 using ETM Landsat satellite 7 images and OLI Landsat satellite 8 images. Then, runoff was simulated for 1984-1989 based on 1987 land use by SWAT model. For calibration and validation of the model, the SUFI-2 algorithm was used in SWAT-CUP software. Results: The statistical results of the model calibration and validation of the model during the period of 1988-1989 show an acceptable accuracy in runoff simulation. To derive the land use map of 1987 and 2013, the supervised method and the classifier program with the most similarity and the general accuracy of 80% and 85% were used. In order to evaluate the effect of land use change on runoff potential, runoff for 1999 to 2011 period was simulated based on both 1987 and 2013 land use maps. For 1999 to 2011 period, no acceptable accuracy for estimating runoff was obtained when land use maps of 1987 were applied, whereas the accuracy of the calibration and validation increased when 2013 land use was applied. When 2013 land use map was applied, the observed runoff was in the range of the uncertainty band PPU95% of SWAT model. According to the results, the amount of surface runoff has been increased in the recent years. Conclusion: The study of all factors affecting runoff is a difficult and very complicated task and it is necessary to study the effects of different factors using new techniques and models. The results of this study indicated that if the input data is properly prepared for SWAT model, this model has a good performance in runoff estimation. Land use mapping in accordance with the actual conditions of the region can have the greatest impact in the accuracy of the model.

Background and Objectives: Flood is one of the deadliest natural disasters in the world, which causes enormous damages to human societies and changes in environment. In recent years, the possibility of floods in many parts of the world has been a source of concern for people and governments. This has caused the need for more experienced managers and flood engineers to reduce the flood impact on the society and environment. Flood forecasting is one of the most promising methods of flood risk management that provides valuable information for flood warning services and people and organizations in emergency situations will have enough time to prepare for flood control measures. Materials and Methods: In this study, standardized precipitation index (SPI) and standardized precipitation-evapotranspiration index (SPEI) in Darzikala and Sangadeh weather stations located in Kasilian basin, Mazandaran province were calculated to determine the wet period. Then, in order to explore the efficiency of SPI and SPEI in flood detection, the results were compared with river discharge time series in Valikbon gage station. The parameters for the diagnosis probability (POD), the False Warning Ratio (FAR) and the Critical Position Indicator (CSI) were used to assess the success rate of these indicators in flood detection at the stations. Results: The results showed that the maximum and minimum POD, CSI and FAR were 0. 89 and 0. 68, 0. 71 and 0. 61, 0. 32 and 0. 11, respectively, for SPI and SPET indices. The trend analysis of mentioned indices showed that the SPEI index was relatively better than SPI due to the use of temperature data and hence the calculation of evapotranspiration, especially at the end of spring and summer in the Kasilian basin which has rainfall– snow regime. Conclusion: Based on the POD, FAR and CSI statistics, it is suggested that due to the use of temperature data for snow melt, especially in spring and summer, the application of SPEI index is more suitable than SPI for flood forecasting in rainfall-snow regime. The SPI index is also an important indicator because of its ability in providing desirable results in flood forecasting with only one parameter and also due to this fact that the rainfall is the only accurate data with appropriate historical period in all watersheds and at least two organs in the country are collecting information about it.

Background and Objectives: Soil temperature is an important and effective variable influencing the different biophysicochemical processes in soil. Soil temperature also has a direct and indirect impact on plant activities and has a remarkable effect on the mass and energy transfer rate between soil and atmosphere. With respect to having limited and non-complete soil temperature data, modeling the soil temperature is very important. In this context, SVAT models which are on the basis of the solving the coupled soil heat and water transfer equations have a high importannce and acceptable accuracy. Materials and Methods: To perform this research, a SVAT model was used to simulate the hourly soil temperature in different depths. The synoptic weather station (Saghez station) was selected to perform this research. Based on the measured data of the soil physical properties in different layers and several meteorological variables in a multi-year time period, the hourly soil temperature values were simulated in different soil depths. The Bayesian method was used to calibrate the model by considering 10 main model parameters and by performing 8000 model runs on the basis of the different combinations of the parameter values in their uncertainty range using the Monte-Carlo stochastic method in the 1994 to 2009 time period. Then, the calibrated model was validated in the 2010 to 2014 time period and to evaluate the model performance, three indices including mean absolute error (MAE), mean biased error (MBE) and coefficient of determination (R2) were applied. Results: The bayesian calibration results showed a sensible change in the 10 selected parameter values compared to their default values with a good calibrating process. In the calibration period, the value of all of the performance indices in most cases was improved after calibration process in comparison to the default-value parameters case. The results of model validation showed non-remarkable differences between the model performance indices for two calibration and validation cases and therefore, an acceptable performance of the calibrated model can be expected to forcast the hourly soil temperature values in any desired period so that the coefficient of determination (R2) was obtained more than 0. 9 in all of the studied times and soil depths. However, the model performance did not show a similar behavior during different seasons so that based on the R2 criterion, the lowest model performance was occurred during the winter but on the basis of the MAE criterion, the best and lowest model performance was occurred in the winter and both spring and summer seasons, respectively. The results also showed that the overall tendency of the model simulations is to underestimate the spring and summer and overestimate the autumn and winter soil temperatures and in the annual scale, an overall model underestimation can be recognized. The daily mean soil temperature simulation results showed less error values in comparison to the hourly soil temperature simulations. Conclusion: The overall results of this research showed that although the SVAT model used in this study is suitable for simulating hourly and daily temperature values of different depths of the soil, but by collecting and involving more data like soil moisture data in the calibration process, it is possible to achieve more accurate results than the model. Also, due to the existence of specific processes affecting soil temperature in both summer and winter, it is suggested that the calibration process of model parameters for these two seasons should be done separately.

Background and Objectives: Considering the growing limitation of water resources, a plan is needed to be made in order to optimally use water resources, especially in the agricultural sector which uses most of the water resources. A study was conducted which its objective is to optimally allocate water resources to the Hamidiyeh irrigation network cropping pattern in order to make a plan to manage the water resources consumption trend in the Hamidiyeh irrigation network. Materials and Methods: The water year 2015-2016 was divided into 36 periods which consist of 10 days and multi-objective model was created to allocate water resources to each one of 10 day periods in order to maximize the relative water use efficiency and the revenue-cost ratio using a non-dominated sorting genetic algorithm. Furthermore, another optimization model was created to minimize the error in the yield reduction estimation under deficit irrigation application situation using genetic algorithm. Results: The obtained results of stage wise crop response factors modification model indicated that the estimated values of yield reduction under deficit irrigation application situation using the stage wise crop response factors which were proposed by former studies vary between 16. 5 and 195. 5 percent. The yield reduction amount of more than 100 percent shows an estimation error, while the yield reduction estimated using the modified stage wise crop response factors vary between 8 to 59. 5 percent. The optimal water resources allocation model is a multi-objective model which has more than one optimal solution that none of them is better that the other, and the suitable solution is chosen based on managerial decision taking. As a result, three solutions were chosen as scenarios to be compared with the current water allocation situation. Results indicated that revenue-cost ratio is slightly changed under optimal water resources allocation, but relative water use efficiency is increased at least by 9 percent, and water use is reduced at least by 26 percent. Furthermore, the cultivation area is increased by 192, 189, and 182 hectares in the first, second, and third scenario, respectively. Net benefit was increased by 19. 5 and 10. 7 billion rials (IRR) in the first and the third scenario, however, it was reduced by 8. 4 billion rials (IRR) in the second scenario. Conclusion: The amount of water consumption is considerably reduced and the relative water use efficiency and the cultivated area is increased under optimal water resources allocation which causes reuse of fallow area. Furthermore, net benefit could also be increased depending on the chosen solution.

Background and Objectives: Lateral ditches which are constructed to drain surface flow and protect the road structure under the severe rainfall are eroded by runoff velocity and then sediment as suspended load are transmitted to the river and aquatic ecosystem. Therefore, use of the cost effective, efficient and environmental techniques is essential for protecting ditches. The objective of this research was to compare the effect of different protective treatments on reduction of sediment yield from the ditch of forest roads as well as the assessing the effect of flow intensity on sediment concentration. Materials and Methods: At first a reach of lateral ditch with a total length of 50 meters was selected along the main roads of district one in the Bahramnia forestry plan in Golestan Province. The longitudinal slope (5% with dimension of 30 × 50 cm) and soil type (texture, porosity and moisture) of selected reaches were same. Five sub-reaches (treatments) each of with a length of 10 meters were considered for establishing the protective treatments including riprap, grass cover by Festuca, cotton geotextile, picket and wattle by local slash and control. Flow simulation was done for ten minutes at two flow rates of 5 and 10 L S-1 using a tank with capacity of 6000 liters equipped with motor-pump. Sediment sampling from the runoff was carried out at the end of each sub-reach every minute. Samples were transported to the laboratory and there sediment concentration was calculated in gram per liter. Runoff flow velocity in different treatments was measured using an electromagnetic flow meter. Results: Sediment concentration and runoff velocity in treatments of riprap, grass cover by Festuca, cotton geotextile, picket and wattle by local slash was significantly lower than that of control. Increasing flow rate from 5 L S-1 to 10 L S-1 caused no significant change in sediment concentration (except for control and riprap treatments) and runoff velocity (except for control and cotton textile treatments). Sediment yield from riprap and control treatments under the flow rate of 10 L S-1 was significantly higher than that of 5 L S-1. Moreover, runoff velocity from cotton textile and control treatments under the flow rate of 10 L S-1 was significantly higher than that of 5 L S-1. Conclusion: Treatments of picket and wattle, riprap, grass cover by Festuca and cotton geotextile in ditch with low flow rates (5 L S-1) and treatments of cotton geotextile, picket and wattle with local slash in high flow rate (10 L S-1) can be used for a forest road with dimension 30 × 50 cm, slope 5%, clay soil with porosity 57% because of their high efficiency in reducing sediment yield and runoff velocity.

Background and Objectives: Changing the number of frosty days in the future, which is important for agriculture and development, can be one of the consequences of climate change and the phenomenon of global warming. Understanding how and when it happens can help the agricultural sector. The purpose of this study is to determine the change in the number of frosty days in the future period (2068-2015) compared to the base period (1961-2014) for the Gorgan station. Materials and Methods: In order to compare the number of freezing days in the base and future periods, daily data on the minimum temperature of the Gorgan station was received from the Iranian Meteorological Organization during the period 1966-2014. The latest available scenarios of the Fifth Report of the Intergovernmental Panel on Climate Change (AR5 2014), which include RCP scenarios, were downloaded from the Canadian Climate Change Web site and, using the SDSM macroeconomic statistics software, data for the upcoming period (2068-2015) in the region was scaled down. Afterward, the number of frosty days in the base period and the scenarios was calculated. Then, Wilcoxon test showed a significant difference between the mean numbers of frosty days. Result: In general, the purpose of this study is to investigate the total number of freezing days during the observation period and compare it with different scenarios in the future. In order to achieve this goal, using the Wilcoxon test, the mean of observational data with three scenarios 2. 6, 4. 5 and 8. 5 respectively. This comparison shows a significant difference between the means. (The compare means is significant when it is less than 0. 05). Meaningful meanings indicate that frosty days will be reduced significantly in the future. The results of this research indicate that in the next 54 years (2015-2068), the minimum temperature will increase for Gorgan station and the number of frost days will significantly decrease. The average number of freezing days in the base period (1961-2016) is about 16 days, in the upcoming period until 2068 in the scenario 2. 6, about 8 days, in the scenario 4. 5, about 7 days and in the scenario 8. 5, about 6 days. Conclusion: Based on the results of the used models, the comparison of results in the base and future periods indicates a minimum temperature increase and a decrease in the number of freezing days. The significance of the average number of freezing days in the observation and future period indicates a significant and severe decrease of frosty days and low minimum temperatures in the future, which could be a reason for climate change. The findings of this research and similar studies confirm the results of the increase in minimum temperature and also the reduction of the frost phase, which requires a greater awareness of planners to deal with destructive effects of climate change.

Background and Objectives: Industrial dyes are one of the largest organic compounds which have extensive application in different industries. due to the complex aromatic structure and artificially producing process, they are stable compounds in the environments and are resistant to the disappearance. Wastewaters contain dyes induces the surface and subsurface pollution. If these wastewaters discharge without remediation into environment, they can impose irreparable damage to the environments. Therefore, it is necessary to reclaim wastewaters and contaminated soil by using reliable methods. Among the suitable methods for removing dyes, adsorption is the appropriate technique for dye removal. Materials and Methods: In this study, the effect of rice straw biochar (RSB) which is produced at 600˚ C, soil and mixture of soil and biochar on methylene blue adsorption from aqueous environments was investigated. This biochar was chosen because, it had the highest adsorption capacity among all other adsorbents (dicer woodchips, sugarcane bagass, rice husk and rice straw) which was prepared in two different temperatures. First, rice straw was turned to biochar at 600˚ C. Then biochar was mixed with sandy soil which was taken from alluvial plains of Tajan area of Sari, Mazandaran province at ratios 1, 2. 5 and 5 (w/w). Methylene blue dye solution was prepared from methylene blue powder, and 40 mL of solution with concentrations of 30-300 mg/L and pH=7 was added to 0. 1 g biochar, soil and mixture of soil and biochar and finally, methylene blue sorption isotherms were determined for biochar, soil and mixture of soil an d biochar. Experiments were performed in a completely randomized design with three replications. Results: The results of fitting the data to the Langmuir and Freundlich isotherm model showed that methylene blue adsorption on the RSB produced at 600˚ C, soil and mixture of soil and biochar matches with the Langmuir isotherm model. Biochar, mixture of biochar and soil and soil had the maximum adsorption capacities with amounts of 27. 85, 3. 272 and 17. 953 mg/g, respectively. Due to biochar high specific surface area, high cation exchange capacity and the presence of functional groups, it had a high adsorption of methylene blue. Conclusion: In general, the results showed that methylene blue adsorption isotherms by the biochar, soil and mixture of soil and biochar were L-shaped and there was a high affinity for absorption. Results also showed that incorporation of biochar to soil enhanced the adsorption capacity of soil, thus it can be concluded that RSB could improve methylene blue adsorption in soil environment.

Background and Objectives: The increase of irrigation efficiency is a technique for water conservation; therefore, appropriate management and the application of efficient methods in order to maintain enough water in the soil are essential for optimum utilization of scarce water resources of the country. The use of super-absorbent polymers offers effective ways of saving water in agriculture. However, before selecting a suitable polymer, determining an appropriate model is essential. The purpose of this study was to study the inflation properties of superabsorbent polymers in a peripheral environment by controlling the amount of swelling and determining the gel infiltration kinetics to determine the fluid adsorption model in polymers. Materials and Methods: Water absorption model was measured by two superabsorbent polymers from the polyacrylamide family, abbreviated T-A200 and T-A100, by performing a four-replicate experiment until the moment of equilibrium momentum and cumulative swelling and absorption. The fluid was immersed in distilled water. Then, the data diagram was obtained based on changes in the instantaneous absorbed ratio of the solvent relative to the equilibrium state with the time of drawing and the trend of adsorption of solvents. To determine the penetration mechanism, the corresponding model was used and finally, the coefficients n and k were calculated. Results: Absorption of fluid in heterogeneous environments such as gels was accompanied by considerable changes. The plotting of the graph in terms of the amount of solvent adsorbed instantaneously with time and the results showed that in all cases n was less than 0. 5 and as a result, the mechanism of transferring the solvent into the networks of the polymers is well adhered to Fick's law. Conclusion: The appropriate super-absorbent polymer in agriculture should be able to minimize water absorption in the least amount of time, thus effectively preventing water loss in rain or irrigation. To prove it, the model should follow the Fick diffusion which penetration rate is lower than the speed of molecular relaxation and only diffusion phenomena is effective through the transfer of ground-penetrating, so, molecular relaxation phenomenon does not have an effect on the transfer of ground-penetrating. Consequently, after any deformation or swelling, the polymers quickly reached a new balance and stresses will quickly vanish; therefore, it does not have any effect on the speed of penetrating component. In this study, the penetration of the fluid into the polymer followed the Fick model. Hence, this model would certainly be recommended to periodic swelling ability in agricultural purposes.

Background and Objectives: Soli erosion plays an important role in desertification process that its evaluation leads to better understanding of desertification potential. The sparse vegetation cover, low humidity and the scarcity of rainfall can make Jaz-Murian region prone to soil erosion and desertification. The purpose of this study was to assess the potential of desertification in the Jaz-Murian region on the basis of erosion criteria and using IMDPA model. Materials and Methods: In this research, the work unit map was created using geology, land use maps and Landsat 8 satellite imagery data. Water erosion indices were weighted based on the IMDPA method and the IRIFR model was applied to evaluate wind erosion. Finally, in order to represent desertification hazard, the water and wind erosion criteria were combined with each other in ArcGIS 10. 1 software by calculating geometric mean of their indices. Results: The findings of this research showed that the largest area in this region (approximately 5674 km2) classified in high class of desertification hazard. This means that the erosion factor play an important role in desertification process in the Jaz-Murian region. The research findings showed that in comparison with water erosion, the wind erosion has a higher effects on desertification. The most important reasons for this are the low level lands, recent droughts and subsequently the reduction of the humidity that can help to separate the soil particles and increase the erodibility. Also, the results of estimation of erosion rate showed that the work units including: "clay plain covered by degraded Nebka and Reboh” , “ clay flat with separated Tamarix and Prosopis species” , “ clay and salty lands covered by dominant vegetation of Seidlitzia rozmarinus and Hamada salicornica” and “ Erg and sand dunes” showed the highest sensitivity to wind erosion that priority should be given to desertification plans aimed at controlling this phenomenon. Conclusion: According to the results obtained in this study, the majority of the studied area (97. 2%) is considered as a severe erosion criterion for desertification. In this regard, the need for more emphasis on the role of soil erosion factor in the development of management plans to control the phenomenon of desertification in the region is of great importance. Therefore, restoring vegetation and protecting it from degradation, taking ecological considerations and prioritizing areas that are sensitive to erosion, can help to reduce the effects of erosion in the region and desertification.