Journal of Water and Soil Conservation
Year:2020 | Volume:27 | Issue:2|Papers Count:15

Background and Objectives: Arsenic contamination is one of the serious environmental challenges in developing countries. Contaminated water is the main source of human and animal exposure to inorganic arsenic. There are various physicochemical and biological methods to remove arsenic from aquatic environments. Compared to the advantages and disadvantages of arsenic removal methods, the adsorption method is preferred over other methods due to its ease of use and low cost. Iron-rich materials have a high capacity to adsorb arsenic from aqueous solutions. The objective of this study is an assessment of arsenate removal from water using biochar modification by iron salt, which can be used for the recovery of arsenate contaminated water resources for drinking water supply and reuse of industrial effluents. Materials and Methods: In order to prepare iron modified biochar 0. 1 (0. 1FeBC) and 0. 4 (0. 4FeBC) ratios of FeCl3. 6H2O were added to apple pruning residues powder and pyrolized in the furnace for an hour at 300 ° C under limited oxygen condition as well as a control sample without iron. SEM images were used for characterization of the morphology of the adsorbents. The isotherm experiment was carried out at initial concentrations of 0, 1, 2, 4, 6, 8 and 10 mg arsenate/L and remaining arsenate in solution was determined using hydride generation atomic absorption spectroscopy (HG-AAS). Experimental data were fitted to Langmuir, Freundlich, Temkin, and Dubinin– Radushkevich isotherm models and parameters such as apparent energy of adsorption (E), adsorption efficiency, Gibb’ s free energy (Δ G) and separation factor were calculated. Results: Iron modified the surface properties of biochar and increased the amount of the granular compounds on the adsorbents surface. The results showed that by increasing the adsorbent iron content, the removal of arsenate from solution increased and the highest removal efficiency (86%) was obtained for the 0. 4FeBC adsorbent at 1 mg Arsenate/L. The ability of the Freundlich model to simulate the process of arsenate adsorption by iron-modified adsorbents was higher than the Langmuir, Dubinin– Radushkevich and Temkin models. Along with increasing the iron content in the adsorbents Freundlich (KF and n), Temkin (KT and A), Langmuir (KL and qmax) coefficients increased, while the Dubinin– Radushkevich (KDR) coefficient and separation factor (RL) decreased. The highest value for the maximum absorption capacity (qmax) was obtained for 0. 4FeBC in the amount of 7. 66 mg of arsenate per gram of adsorbent. According to the values of apparent energy of adsorption (E), adsorption process for unmodified biochar is physical (less than 8 kJ/mol) and for the modified biochar is chemisorption. Based on Gibbs free energy (Δ G) values, the adsorption process of arsenate by adsorbents is spontaneous. Conclusion: According to the results of this study, iron-modified biochar due to local accessibility and easy application can be considered as an inexpensive absorbent for removal of arsenate from water.

Background and Objectives: Soil contamination with heavy metals has become a global concern because of its adverse effects on ecosystem health and food security. Soil amendments including biochar can reduce the bioavailability of heavy metals in contaminated soils and reduce their risk of entering the food chain. Biochar is a carbon-rich material obtained by pyrolysis of biomass, such as agricultural residues and manures in conditions without oxygen or with limited oxygen content. Recent studies have shown that biochar also has great potential for immobilizing heavy metals in soil, because of its highly porous structure, active functional groups, and generally high pH and cation exchange capacity (CEC). In the country, most of the studies on biochar are related to calcareous soils or aqueous solutions and biochar has received little attention as an efficient adsorbent for the adsorption of heavy metals in acidic soils. The goal of this study was to investigate the effect of biochar derived from carrot pulp on properties of acidic soil and adsorption of lead and cadmium in soil. Materials and Methods: In this study, biochar derived from carrot pulp was produced through pyrolysis at 550 ° C with a heating rate of 25 ° C min-1. Carrot pulp biochar was added to acidic soil at 0, 4 and 8% application rates and was incubated for 60 days. After the incubation period, to investigate the effects of time on Cd and Pb adsorption, 25 mL of 400 mg L− 1 of Cd and Pb were added to 1 g of soil samples and then samples were shaken for different times (4, 8, 12, 16, 20, 24, 28, 32, 36 and 40 h). Then, the concentration of Cd and Pb were measured. The results were fitted to pseudo-first-order, pseudo-second-order, and Elovich kinetic models. To determine the adsorption isotherms of Cd and Pb, 25 mL of heavy metals solution with concentrations ranging from 0 to 400 mg L− 1 were added to 1 g of soil samples, and then samples were shaken for 24 h, and finally the adsorption data were fitted to Langmuir, Freundlich and Temkin isotherm models. Results: The application of biochar significantly increased the pH, cation exchange capacity and electrical conductivity of the soil, although the 8% application rate more effective than the 4% application rate in increasing the pH, cation exchange capacity and electrical conductivity of the soil. The results of fitting the data to the Langmuir, Freundlich and Temkin isotherm models showed that the surface adsorption of Cd and Pb on the control soil and soil treated with biochar is consistent with Langmuir isotherm model. The pseudo-second-order kinetic model was introduced as the best kinetic model of adsorption of Cd and Pb. The maximum adsorption capacity of Cd and Pb increased from 649. 27 mg kg-1 and 846. 71 mg kg-1 (in control soil) to 2078. 29 mg kg-1 and 3182. 7 mg kg-1 (in soil treated with 8% biochar), respectively. Conclusion: This study showed that carrot pulp biochar increased the adsorption of Cd and Pb in acidic soil by increasing the pH and cation exchange capacity of the soil. Therefore, carrot pulp biochar can be used as an effective and inexpensive adsorbent to improve acidic soil properties and increase the adsorption of Cd and Pb in soil.

Background and Objectives: Petroleum products are one of the most widely used chemicals in the modern world. Petroleum hydrocarbons have become a global problem for the environment. These compounds are highly resistant to the environment and are harmful to human health. Application of bioremediation process to remove polyaromatic hydrocarbons from contaminated soils is one of the most economical and desirable options. The purpose of this experiment was to investigate the percentage of hydrocarbon removal from soil polluted with hydrocarbons (crud oil) by sorghum, barely and bermudagrass with and wihout Psudomonas putida and Azosprillum brasilense. Materials and Methods: In this study, simultaneous efficiency of phytoremediation and bioremediation in removal of crude oil from soil was investigated. For this purpose, a factorial experiment was conducted in a completely randomized design with three replications. The treatments consisted of three levels of soil contamination with oil (0, 4 and 8% oil), four herbal treatments (no plant, bermudagrass (Cynodon dactylon), sorghum (bicolor Sorghum) and barely (Hordeum vulgare() and three bacterial treatments (no bacteria, Psudomonas putida and Azosprillum brasilense). To do the experiment, samples of five kg soil samples were contaminated with different amounts of crude oil and poured into plastic pots. After six weeks to reach the equilibrium of contaminated soils, these soils were inoculated with Pseudomonas putida and Azospirillium brasilense bacteria, then in polluted soils of inoculated with bacteria and no inoculated three gramineae species were planted. Ninty days after planting, plants were harvested. Results: The results showed that interaction effects of treatments on the percentage of crude oil removal were significant at 1% probability level. Percentage of crude oil removal was significantly increased by plant cultivation alone, bacterial inoculation alone, and combined plant and bacterial application. Cultivation of plants was more effective than soil inoculation with bacteria in reducing the concentration of oil and plant increased bacteria function significantly so that, there were significant difference among treatments of plant alone, inoculation with bacteria alone and plant + bacteria. The highest removal percentage was observed in combined application of plant and bacteria. In each treatment with soil inoculation with bacteria, with increasing levels of oil pollution, dry weight of plants decreased but, at each level of crude oil pollution, inoculation of soil with bacteria, the dry weight of shoot increased. Soil inoculation with bacteria improved dry weight of shoot through removal of oil pollution in soil. Chlorophyll concentration decreased significantly with increasing level of contamination. While, inoculating the soil with bacteria and reducing the negative effects of oil contamination and nitrogen availability on the plant, chlorophyll concentration in fresh leaves increased. With increasing levels of oil pollution, the mean proline concentration in fresh leaves of plants was significantly higher than that of control. Its highest concentration (in each plant) was obtained at 8% of crude oil pollution. Inoculation of soil with bacteria in polluted soils and non-polluted soils increases the amount of proline in the leaves of plants. In each level of crude oil pollution, inoculation of soil with bacteria, the proline concentration of leaf of plants increased. The highest concentration of proline was measured in the treatment of the highest oil pollution level (8% crude oil pollution) and inoculation with Pseudomonas putida. Conclusion: Establishment of plant with microorganisms can be considered as a key component of the strategy to remove hydrocarbons. Consequently, these bacterial and plant species can be used for the biodegradation of soils contaminated with crude oil.

Background and Objectives: The occurrence of climate change and its impact on surface water and groundwater resources, along with inappropriate management of water resources have led to an increase in the social and environmental vulnerability of river systems. Assessing the vulnerability of river basins, especially in developing countries such as Iran is essential and is considered as one of the main priorities of the water resources planners for the sustainable management of these resources and for the formulating of policies consistent with the regional conditions. In this line, this paper focuses on the assessment of the vulnerability of the Jarahi River Basin. Materials and Methods: The study area of this research, the Jarahi River Basin, is located in southwest of Iran with an area of about 24000 square kilometers and a population of about 870000 people. In this research, the River Basin Vulnerability (RBV) method was used to assess the vulnerability of the Jarahi River Basin. This method examines the vulnerability of ecosystem and human simultaneously and consists of a total of six main indicators including ‘ governance’ , ‘ economic status’ , ‘ social condition’ , ‘ environment’ , ‘ water stress’ and ‘ natural hazards’ indicators. In this method, data are evaluated quantitatively. The combination of these indicators is based on a raster summation algorithm which can be carried out in the ArcGIS platform. Results: The anlysis shows that the vulnerability of the Jarahi River Basin corresponding to each of the indicators of governance, enconomic status, social condition, environment, water stress and natural hazards are 0. 76, 0. 41, 0. 061, 0. 43, 0. 44 and 0. 84, respectively. The results exhibit that the Jarahi River Basin is severely threatened by natural hazards and in particular, the flood hazard threatens all parts of the river basin. It is also exposed to high water stress. The highest water stress (0. 76) associated with the Shadegan sub-basin that is located in the southern part of the basin. In addition, the Saiddon sub basin has the lowest literacy rate among the sub basin of the Jarahi River Basin with the rate of 79%. A significant part of the Shadeghan sub-basin exhibits considerable environmental impacts, interpreted as a discernible sign of human footprints in the area. Conclusion: Generally, in the Jarahi River Basin, the vulnerability of three indicators, namely governance, water stress and natural hazards are quite significant. In particular, flood assessment analysis shows that almost all the river basin is highly susceptible to flood hazard. Also, seismic hazard threatens a considerable portion of the Behbahan and Takht-E Deraz sub-basins. Moreover, regarding the natural hazards, given the high potential of drought, flood and earthquake occurrences in the research area, it is possible to somewhat reduce the incurred damages caused by these phenomena in the river basin by means of paying due attention to knowledge, awareness, planning and efficient management. The results regarding the water stress show that almost half of the basin (mostly the Shadegan sub-basin) suffers from high water stress. Concerning the water stress indicator, given that the excessive use of water in the agriculture sector is mostly responsible for the high vulnerability state, changing the current land-use and accordingly the cropping pattern in the Jarahi River Basin will potentially have a positive impact on water stress indicator. Through controlling corruption, improving Iran’ s political stability status and reducing the government fragility index, an improvement in the governence indicator can be achieved.

Background and Objectives: Environmental stresses are a major obstacle to world food supply. There is relatively little stress-free arable land where crops reach their potential yields. For example, about 45 percent of the world's agricultural lands, with 38 percent of the world's population, are experiencing temporary or permanent drought (Bot et al., 2000). Sesamum indicum L., due to its tolerance to drought and heat, is very important in the development of arid and semi-arid regions as summer crop (Aien, 2013). In one study, sesame cultivar Darab 14 based on MP, TOL, SSI, HARM and STI indices was introduced as superior cultivar under normal conditions and moisture stress. Due to its high content of sesame oil (42-52%) and good quality (low cholesterol and some antioxidants), it plays an important role in human health and on the other hand, it is tolerant and drought tolerant (Afshari et al., 2014). The purpose of this study was to investigate the effect of drought stress by applying different levels of surface irrigation and identifying superior cultivar based on stress indices. Materials and Methods: Study and evaluation of drought stress indices in surface irrigation on sesame seed yield and its components, seed oil yield, seed oil percentage and water use efficiency of experimental seed were conducted at Behbahan Agricultural Research Station in 2014. The experiment was conducted as split plot in a randomized complete block design with three replications. Irrigation at two levels (irrigation after 100 and 200 mm evaporation from Class A pan, respectively) was evaluated as main factor and cultivar at 5 levels (local Behbahan, SG37-92138, SG51-92138, SG53-92138 and SG55-92138) as sub-factor. Results: Comparison of mean water use efficiency in irrigation and cultivar interactions showed that 100 mm evaporation from Class A pan and V5 (SG55-92138) evaporation with water use efficiency of 0. 272 kg/m3 sesame seed was superior. The mean water consumption in one year of experiment in 100 and 200 mm evaporation from Class A pan was 547. 5 and 438. 6 mm, respectively. The results of Pearson correlation coefficient showed the highest correlation of 1000 kernel weight after number of kernels per capsule with grain yield was r = 0. 9616, which indicates the effective role of 1000 kernel weight gain in enhancing grain yield. The highest values of STI, MP, GMP, HM and YI were calculated with V5 (SG55-92138) with values of 1. 538, 1037. 1, 1024. 7, 1011. 5 and 1. 548, respectively. The increase in the above indices in cultivar V5 (SG55-92138) compared to other cultivars caused it to be introduced as superior treatment for drought stress. The decreasing trend of sesame yield caused by dehydration stress decreased SSI, MP and TOL indices and, on the contrary, decreased sesame yield, and led to bullish changes in STI, GMP, HM, YI and YSI indices. Conclusion: Comparison of mean interaction effects between irrigation and cultivar in terms of water use efficiency showed that water use reduction in stress treatment decreased water yield in these treatments compared to non-stress treatment. The effect of reducing water use was even to the extent that it failed to cover the continuous decrease in yield in return for water consumption and continued to treat 100 mm evaporation of Class A pan despite more water consumption than the 200 mm evaporation treatment of Class A pan. The highest water use efficiency among treatments was due to increased yield. The positive and significant correlation between number of capsules per plant and number of seeds per capsule (r = 0. 9688) showed that with increasing number of capsules per plant and number of seeds per capsule, grain yield increased.

Background and Objectives: Assessment of performance of watershed management measures is always done by comparing watershed responses before and after operations. This process causes the effect of the operation to spread over time and not to see its true effect and consequently, the weakness of that series of operations will remain unknown over time. Therefore, considering the importance of check dams in watershed management programs in Iran, the goal of this study is determination of real-time impact or life span of check dams in controlling discharge and sediment load and assessing of their impacts in Kond watershed located in Tehran province. Materials and Methods: First, useful lifespan of check dams has obtained based on precipitation-runoff double-mass curve and field surveys. Then, the study period (1999-2015) is divided into three periods: before the construction of the check dams (first period), the useful lifespan of the check dams (second period) and the end of the useful lifespan of the check dams (third period) and the discharge and sediment load changes at the outlet of watershed are investigated and compared with the common approach. Sedimentation rate curve methods were also used to estimate the sediment load in each period. Results: The time points of occurrence of slope fractures in double mass curves as well as field observations indicate that the duration of impact (useful lifespan) of check dams in the Kond watershed was on average four years (from 1999 to early 2003). The results of impacts assessment of the check dams in the study area indicate that despite the constant precipitation conditions, the outflow discharge and the maximum, average and minimum characteristic discharges in the second period, compared to the first period, has decreased by 43, 49. 66, 53. 28 and 100%, respectively. The amount of sediment load reduction in the second period is much more noticeable than the first period and is 92. 47%. However, at the end of the useful lifespan of check dams (third period), the amount of discharge and sediment load has increased, returning to the level of the first period. Comparison of the results of this assessment approach (determining useful lifespan) with the common approach (before and after project implementation) also shows that in the common approach due to the distribution of the effect of operations over time, the performance of check dams will be measured at half their actual performance. Conclusion: The results of this study show that considering the useful lifespan in the evaluation process will provide more realistic results. In fact, the efficiency of check dams in Kond watershed is considerable during their useful lifespan, but their short useful lifespan is a significant weakness of this type of watershed operation. In addition, relying on check dams to stabilize watersheds has not been a successful approach and only prevents to exit sediment production from the watershed and, for this reason, in the third period, the watershed response has returned to the pre-operation conditions (temporary effect). Therefore, the benefits of watershed management measures in the Kond watershed were off-site impacts and the on-site impacts were limited to reducing the slope of the main stream. In fact, in order to increase the life span of check dams, watershed management measures with on-site impacts should be prioritized, which this in itself requires erosion control at the source (i. e. the slopes).

Background and Objectives: Amarantuse farming is a way to increase biodiversity. It has high photosynthetic efficiency and is resistant to drought conditions, so it is suitable for cultivation in arid regions and reducing irrigation costs. The desirable agronomic traits (high vegetative growth rate in hot months of the year, drought tolerance and water productivity) and its qualitative (high levels of protein in seed and forage) make this plant a valuable forage plant. Materials and Methods: This experiment was conducted to investigate the quantitative and qualitative yield and water use of forage amarantuse in Golestan province. The experiment was conducted as split plot in a randomized complete block design with three replications. The amount of water consumed (including full irrigation, 75%, 50% and 25% of total irrigation) were in the main plots and the amarantuse varieties (including two cultivars Cim and Loura) were sub-plots. Results: Analysis of variance showed that the simple effect of cultivar and the simple effect of irrigation on plant height, fresh forage weight, fresh and dry stem weight, total dry matter weight, water productivity (based on forage fresh weight yield), insoluble fiber yield were significant. The effect of irrigation on all studied traits was significant at 1% level and two traits of protein yield and water productivity (based on dry matter) were only affected by irrigation regime. Interaction effects of cultivar irrigation on leaf traits, fresh and dry weight of leaves, leaf to stem ratio, insoluble fiber (NDF), percentage of crude fat, lignin, calcium and phosphorus were significant. Results of mean comparison showed that dry matter yield in Cim (6 ton/ha-1) was higher than Loura (5. 5 ton/ha-1). The highest water productivity based on fresh and dry weight was 17. 1 and 2. 2 kg/m-3, respectively, with 75% of total irrigation. The highest protein yield was obtained in the complete irrigation treatment and by reducing the amount of irrigation by 25%, the total amount of protein decreased. The highest and the lowest protein content in irrigation treatments were 947 and 433 kg ha-1, respectively. Conclusion: According to the results of this study, Cim was superior to Loura for most of the agronomic and qualitative traits of forage, so that in terms of leaf and stem weight, leaf to stem ratio, phosphorus and especially water productivity. Repeating these results in similar experiments and considering the results, it is advisable to obtain high quality forage Cim in Gorgan climate conditions and to save water (increase productivity), Irrigation can be adjusted to 75% of the water requirement.

Background and Objectives: Iran is located in a warm and dry area and optimum consumption of water by a method that does not damage the plant is of great importance. Since there no research has been on the effect of bentonite and superabsorbent polymer on drought tolerance of chicory in Birjand city, and from water optimization cases, use of bentonite and superabsorbent polymer has been, in this study, the effect of different cultivation litter on the performance of chicory was investigated. Materials and Methods: The experiment was conducted at the research farm of the Faculty of Agriculture, University of Birjand, 2017-2018. The growth period was 120 days. In this study, the effects of bentonite, superabsorbent polymer, drought stress and the combination of bentonite and superabsorbent polymer were investigated on parameters of leaf area, fresh and dry leaf weight, relative water content of leaf, fresh and dry root weight and water use efficiency of chicory. This research was a completely randomized design with treatments including irrigation as main factor at two levels of 50% and 100% water requirement and cultivation litter as sub factor at 6 levels without superabsorbent and bentonite (witness), 125 kg superabsorbent polymer per hectare, 4. 5 kg bentonite per plot, 2. 5 kg bentonite per plot, 4. 5 kg bentonite per plot + 125 kg superabsorbent per hectare and 2. 5 kg bentonite per plot + 125 kg superabsorbent per hectare. Results: Generally, drought stress had a significant effect on chicory yield. Also, the highest average dry weight of leaf in effect of irrigation and different levels of cultivation litter at two levels of 100% and 50% irrigation was 3686. 66 and 2453. 33 kg/ha, respectively. The highest average in effect of irrigation and different levels of cultivation litter on root fresh weight at two levels of 100% and 50% irrigation was 3626. 6 and 2526. 6 kg/ha, respectively and the highest average root dry weight in effect of irrigation and different levels of cultivation litter at two levels of 100% and 50% irrigation was 1276. 6 and 903. 3 kg/ha, respectively. According to the obtained data from this study, the lowest amount was related to the witness treatment and the highest amount was related to the combination treatment of 4. 5 kg bentonite and superabsorbent polymer. Conclusion: The results showed that drought stress treatments was effective on all investigated traits and reduced these traits. Application of different cultivation litter had positive effect on plant growth and was able to increase plant resistance to water stress and show the highest yield of chicory in Birjand climate conditions.

Background and Objectives: Water and tillage-induced soil erosion on steep slopes farmlands are primary causes of land degradation process that gradually change land morphology. Measurement of soil erosion and sedimentation in most watersheds are nearly impossible. So soil erosion modelling and simulation to understand the processes of soil erosion, to predict runoff and soil erosion and also to determine the best management practices of soil conservation is highly important. Materials and Methods: Area of study (Sample sub-catchment) is a sub-watershed of the Kachik watershed in Golestan province, which is one of the sub-basins of the Gorganrood basin. This area is around 197 ha which completely covered with fertile and erosive loess deposits and is a part of Iranian Loess Plateau (ILP). In this study, WaTEM / SEDEM version 2004 used to estimate water and tillage erosion. After soil sampling in 20 different location respected to the model based sampling method on minimax approach, 137Cs activity determined, and all three distinct erosion phases prepared. Finally, erosion map using 137Cs by considering conversion models including Mass Balance II for farmland and Diffusion and Migration for other land uses produced. Then the erosion and sediment point map produced separately for model evaluation. Results: Using 137Cs radionuclide, 90% of the soil measurement locations devoted to erosion. Mean annual soil erosion using radionuclide conversion models was 21. 1 ton ha-1. This rate of soil erosion regards to 97% SDR (Sediment Delivery Ratio) illustrates high potential for sediment production in the area of interest. Mean of water and tillage erosion by WaTEM/SEDEM were 8. 28 and 4. 87 ton ha-1 year-1 respectively in erosion locations and this rate for sediment was 18. 14 and 7. 89 ton ha-1 year-1 for sediment zones as well. Soil erosion and sedimentation rate using WaTEM/SEDEM model was estimated to be 1. 46 and 0. 85 ton ha-1 year-1 in turn. SDR for WaTEM/SEDEM in this study was around 58%. Conclusion: Given that the entire study area covered with sensitive and fertile loess deposits, and a significant percentage of area devoted to farmland, so water and tillage induced soil erosion is of great importance. The results of this research indicate a low estimation (under-estimation) of the WaTEM / SEDEM model compared to the actual values (measured 137Cs). As a result, WaTEM / SEDEM erosion model is not effective in the loess deposits of the northeast of Golestan province. On one hand spatial pattern of water and tillage induced soil erosion can be used in soil and water conservation practices. On the other hand, pertaining to large vast area devoted to farmland in Gorganrood Basin, tillage erosion should be taken by decision maker. Although for higher certainty, it is necessary to calibrate the model and repeat its implementation in other watersheds.

Background and objectives: Water as the most scare input in the production of agricultural products is not only a limiting factor for agricultural activities, but also is obstacle to other economic and social activities. The limited water resources of Iran, regardless of inter-year variations, are almost constant. Water supply of different sectors faces a lot of constraints with increasing population and development in different dimensions and rising standards of living. So, we need to look for suitable solutions for water demand management. Implementing policies that increase the incentive for consumers to save and prevent the loss of consumption of this valuable input is very effective and important. One of these policies is the pricing of water resources in different ways in the agricultural sector. Investigation of internal studies on water valuation shows that there is a great difference between the economic value of water and paying farmers for water. Water pricing policies based on the economic value of water can be effective in allocation and optimal use of water. Therefore, it is necessary to do various studies in order to apply appropriate policies to the climatic conditions of different regions. Pricing policies in different parts of the country in most cases are used only by area pricing. Due to the problem of water crisis, the growing demand, and the gap between water supply and demand, area-based pricing method does not provide sufficient incentives for optimal use of agricultural water. Therefore, this study examines the different methods of water pricing such as area pricing, volumetric pricing and combination of both. Therefore, this study examines the optimal consumption of water resources for the purpose of water and soil conservation in Gonbad-e-Kavous County, Golestan province. This syudy considered the volumetric pricing and composition of volumetric with area-based methods in addition to area-based pricing method that is the innovation of this study. Materials and methods: Since that different agricultural policies can not be investigated and analyzed in the laboratory environment, so the potential effects of these policies should be investigated by appropriate instruments of policy before, during and after the implementing of policy. Therefore, due to the importance of the subject, in this study, the Positive Mathematical Programming (PMP) model is used to simulate farmers' behavior in the downstream lands of Golestan Dam (1) in Gonbad-e-Kavous County, in the implementation of various water pricing methods such as Area-based, volumetric and mi combined of them. In this study, data were collected using random sampling method and 20 scenarios were investigated. The GAMS software package is also used to analyze the information in this study. Results: The results of this study show that water demand in all three methods (area-based, volumetric and combined) will decrease from 22. 6 to 48. 8% as water price rises in different scenarios. The highest water demand reduction is related to the combined, volumetric and area-based water pricing method, respectively. Conclusion: Applying appropriate water pricing methods makes water be distributed optimally between users based on the value of marginal product and provides incentives to save and prevent loss. Therefore, based on the results of this study, it is recommended to use a volumetric and area-based pricing method in combination.

Background and Objectives: Soil erosion is a major global challenge that its control by appropriate and proportionate methods is necessary. In recent years, various studies have been carried out using amendments and chemical stabilizers to reduce the detrimental effects of runoff and soil erosion. Environmental problems, low efficacy and time-consuming, low availability and high volume requirements have challenged the use of amendments in the usual form. Therefore, due to the proper performance of the amendments to reduce runoff and soil loss, improving the quality of the amendment is inevitable. Nowadays, various wastes are currently produced in important industries, including wood and papermill. In this regard, the fine corrugated and small particles in the effluent of paper mills can be mentioned. Residual fine amendments is a part of fibers that are unavoidably crushed in paper production and recycling processes. Therefore, due to the problems caused by the excessive amount of fines in the process of paper production and the ability to store water in the soil, it seems that it can be used as a natural amendment to reduce runoff and soil loss. Materials and Methods: The present study was carried out to investigate the effectability of runoff generation and soil loss from fine corrugated amendments at small experimental plots. To conduct the study, the soil carried out from the marginal area of the Marzanabad-Kandalous region located in the west of Mazandaran Province. The soil was air-dried and then crossing a 3 mm sieve to put into 50×50 cm plots with a height of 30 cm was filled from the bottom to a depth of 18 cm of mineral pumices as a drainage layer and for the top layer of soil 2 and 8 mm. Treatments were studied at three levels of 0. 5, 1 and 1. 5 )L m-2( and each with three replications in liquid form and uniform spraying on 18 plots with pure water additive and control (dry) and in laboratory scale under rainfall simulation was performed with intensity of some 70 )mm h-1( and duration of 30 minutes. Results: The results showed that use of fine amendment with three levels of 0. 5, 1 and 1. 5 )L m-2( decreased runoff volumes (P>0. 05) and soil losses (P<0. 05) of-35,-5 and +15; 47, 84 and 71% compared to those of the treated plots by fine, respectively. Conclusion: The results of this study show that the application of biocompatible amendment from wastewater of papermills is recommended to prevent entering into the water and soil resources in order to reduce runoff generation and soil losses in sensitive areas of the country facilitating sustainable development. It further leads to reduce runoff generation and soil losses in sensitive areas of the country facilitating sustainable development.

Background and Objectives: Knowledge about land uses and their changes over time is a significant factor in land-use planning and management. This could be used to predict future changes and to take appropriate preventive actions. Public participation approach for land use planning and preventing improper land uses are important practical tools for optimizing water, soil and plant management. In this research, public perception on land use modification in Chehel-Chai Watershed, Golestan Province (Iran), was investigated through field surveys. Materials and Methods: A questionnaire was prepared and its validity and reliability was confirmed by expert elicitation from academics and experts and Cronbach's alpha test (α =0. 87), respectively. The statistical population of this study includes villagers in Chehelchai watershed. The total population of this catchment area is 13, 017 people, of which 373 people were randomly selected from the total statistical population. Descriptive techniques within SPSS software was used for data analysis. Initially, factors that hinder the improvement and optimization of land use owned by the villagers and farmers were identified and scored. Then, the factors that promote the acceptance of land use improvement and optimization operations by farmers and villagers were investigated. Results: The results indicated that the most important factors hindering land use optimization are the lack of financial power of the villagers, lack of support from banks and government institutions, farmers' lack of awareness and low value of agricultural land in terms of production per unit area. The most important factors that could improve land use modification are involvement of people in the formulation of solutions and planning, assurance of ownership of cropland, providing financial and spiritual incentives, farmers' convenient access to engineers and experts and organizing extension and training courses and classes. Finally, by comparing popular acceptance of land use optimization strategies, it has been shown that villagers are in agreement with the option of permanent crop cultivation to optimize landslide slopes, as well as the conversion of sloping croplands to gardens and, if performed and land use improvement program the villagers are prepared to implement land reform programs and if a plan is developed, more than three-quarters of their land will be used for operations and programs. Conclusion: Overall, the most important action to be taken before implementing the watershed programs in the villages is to increase the villagers' awareness of such programs and their involvement in the early stages of the program implementation. As a result, public acceptance of programs in which people participate is greater.

Background and Objectives: Flooding occurrence with rare return periods in most regions of the country and its harmful human and financial effects, which are intensifying often due to human actions, has brought the issue of flood management under more attention. Numerous numerical models have been developed to simulate flooding. These hydraulic models are three types, i. e., one-dimensional, two-dimensional and three-dimensional. Due to the fact that it is necessary to simulate inundation accurately with low cost, a two-dimensional horizontal hydraulic model called Nays 2D Flood was used in the present study. Materials and Methods: The model was used for simulating flood in Arazkuse river reach before joining the Gorganrood River for the event occurred on March 20, 2019, as this phenomenon is one of the rare floods for the region. For this purpose, a DEM with one meter resolution and flood hourly hydrograph were given to the model. Then an appropriate grid was determined and the roughness of the channel and flood plain were mapped using the Google Earth images in the model software environment. Results: The results of this simulation include maps of depth and flood zone and flow rate. The results were evaluated by computing the F coefficient and comparing the area calculated by the model with the images recorded by Sentinel 2 satellite on the same date. The F statistic was calculated 0. 78 in the present study. This number indicates that there is an acceptable match between the area calculated by the model and the area observed by the satellite. The flooded area is 13. 95ha in the satellite image, while the simulated area was estimated 14. 30ha by the model. To evaluate the results, also the depths from rating curve data were used to compare with the simulated depths. The depth calculated by the model is 6. 22 m on 5 April 2019. At that date, the depth of water was observed according to the rating curve measuring 6. 63 meters. The error rate in this evaluation was calculated 6. 18%. Conclusion: These results suggest that the Nays 2D flood model has an acceptable function and it can also be used in future researches. Since the flood movement in a flood plain is in length and width, the two-dimensional models that take into account this fact are preferred to the one-dimensional models. The results of this study and similar researches indicate the good accuracy of these models in simulating the flood zone outside the river channel. Having a high resolution DEM, the model can be used successfully without channel sections’ data when the flood has spread out of the channel bed.

Background and Objectives: River water temperature has both economic and ecological significance when considering issues such as water quality and biotic conditions in rivers. This parameter affects directly other water quality parameters and plays a major role in the quality of aquatic life and habitats. Consequently, with wide application of water temperature for conducting environmental impact assessments as well as for effective fisheries management, it is important to understand the thermal behavior of rivers and related heat exchange processes. Numerous deterministic and statistical models have been used for prediction of river water temperature by researchers. So far the modeling of river water temperatures has generally been based on air temperature. However, the river hydraulics and metrological parameters may have their special effects on river water temperature. Furthermore, there are limited researches undertaken by novel and intelligent algorithms. Hence, in this study, gene expression programming has been used for estimation of the water temperature of the Mohammad Abad River located in Golestan province. In addition to the air temperature, the river hydraulics and metrological parameters were also accounted for modeling river temperature. Materials and Methods: Gene Expression Programming (GEP) is an evolutionary algorithm that uses a population of individuals and selects individuals according to fitness and introduces genetic variation using one or more genetic operators. For the water temperature modeling, the river hydraulics and meteorological parameters including river flow discharge, flow velocity, air temperature, humidity, wind speed and cloud cover during 7-year statistical period (2006-2012) were considered as input parameters and river water temperature was selected as output parameter. Results: Based on the comparison of the results of different GEP models with 1 to 6 input variables, it was concluded that the GEP model with 6-parameters has the highest accuracy in terms of the coefficient of determination and the root-mean-square error. These values were obtained 0. 92 and 1. 8 ˚ C for training data and 0. 90 and 2. 3 ˚ C for the testing data. The mean absolute errors of this model were obtained as 14. 67% and 12. 80% for training and testing phases, respectively, while the error of linear regression model was obtained greater than 38%. Results showed that in comparison with the multiple-linear regression model, the GEP model has better performance for river water temperature estimation. Conclusion: According to the results obtained in this paper, one can use the GEP model for prediction of river water temperature with acceptable accuracy. It is concluded that in addition to the air temperature which has the highest impact on the river temperature, the river flow discharge also has considerable impact.