نشریه پژوهش های حفاظت آب و خاک
سال سی و یکم شماره 1 (بهار 1403)

Plant models are a suitable tool for simulating important agricultural parameters. Due to the existence of environmental stresses in each region, plant models should be evaluated and approved in each region. In recent years, many models have been used to investigate the relationship between water, soil and plants. One of these models is AquaCrop model. The mentioned model should be measured and evaluated for each product and in each specific region. The basis of this model is the reaction of the yield to water productivity, and it simulates the yield by using climate, plant, soil and management variables. Sensitivity analysis helps researchers to have enough information about the effect of each parameter and the amount of its changes in the calibration stage.

The research was carried out in the form of a completely randomized factorial design in the second half of November 1400 and 1401 in the greenhouse. The treatments include three irrigation water treatments (60, 80, and %100 of irrigation water, I1, I2, and I3, respectively), three salinity levels (1, 4, and 7 dS/m, S1, S2, and S3, respectively). There were two types of amendment materials (Biochar (B) and Nanobiochar (NB)) and three levels of Biochar and Nanobiochar (0, 2 and 4% ). At the end of the harvest season, the yield of the product was measured and the water productivity was calculated.Crop data of the one year were used for model calibration and crop data of the second year were used for model validation. The root mean square error (RMSE), mean bias error (MBE), R2 and relative error percentage (RE) were used to test the accuracy and effectiveness of the model. Also, in the research, the sensitivity of the model to the humidity parameters in crop capacity, wilting and in saturated state, plant coefficient for transpiration, effective root depth, upper and lower limit of soil water discharge coefficient for plant development, maximum canopy growth, growth coefficient and reduction of cover and Normalized water productivity was investigated.

According to the comparison of the measured and predicted values of the yield and water productivity of quinoa and the calculation of statistical evaluation indices in both calibration and validation stages, it can be stated that the AquaCrop model has been able to simulate the yield and water productivity in the conditions of using water with different amounts and qualities and Biochar and nanBiochar modifiers. Relative error percentage (RE), root mean square error (RMSE), mean bias error (MBE) and coefficient of determination (R2) for the yield in the validation stage with Biochar amendment material are 0.66, 33.38, respectively. 24.12 and 0.98 and 0.29, 0.33, 0.11 and 0.96 were obtained for water productivity in this stage, respectively. Relative error percentage (RE), root mean square error (RMSE), mean bias error (MBE) and R2 for the yield in validation stage with NanoBiochar amendment material are 0.12, 22.08, respectively. 5.61 and 0.98 and for water productivity at this stage, 0.17, 0.29, 0.05 and 0.96 were calculated respectively. Considering the lower values of the error statistics in the conditions of using the NanoBiochar amendment, it can be said that the model has been able to simulate the yield and water productivity better in these conditions.

According to the obtained results, it can be stated that the Aquacrop model is an acceptable reliable level using the simulation of the yield and water productivity of quinoa plant under different quantitative and qualitative treatments of irrigation water and soil amendment are used and help farmers, designers, experts and agricultural managers as a powerful and efficient tool to choose optimal irrigation management.

Due to limitations in renewable freshwater resources, proper management of resources and demands is one of the key factors for achieving sustainable management. This is a critical factor in achieving sustainable water management. This study aims to investigate the impact of government contractionary policies on the reduction of surface and groundwater rights in the Miandoab plain and quantitatively examining their impacts on groundwater resources. The quantitative modeling of groundwater in the Miandoab plain utilized data from 120 observation wells. Geological, soil layer, and recharge layers pertinent to the region were collected. Groundwater level changes from October 2010 to September 2016 were modeled and analyzed in both stable and unstable)transient) states using the MODFLOW code. The model calibration stages were performed based on adjusting the hydrodynamic parameters of the aquifer, such as hydraulic conductivity and recharge, for 50time steps from November 2010 (70% of the modeling period). The best fit between computational and observational values was achieved both manually and automatically. 30% of the data was used for model validation. The model’s sensitivity to the aquifer’s hydrodynamic coefficients was examined. Finally, various scenarios related to water allocation reduction policies of the region and their effects on groundwater behavior, such as reducing extraction and recharge by decreasing surface water entering the plain, were quantified. The results demonstrated that the Root Mean Square Error (RMSE) was approximately 1 and 1.68 meters for the stable and unstable(transient) states, respectively. The hydraulic conductivity values within the aquifer ranged between 3.5 and 28 meters per day, and the specific yield values varied between 3 to 24 percent. The model exhibited the highest sensitivity to surface recharge and the least sensitivity to specific yield. The Pearson coefficient for the calibration and validation period of the unstable state exceeded 0.98, indicating a high degree of model accuracy. All effects of the government’s contractionary policies on reducing 40% of surface water and balancing the aquifer with the levels of natural aquifer recharge were implemented. Given that the average drop in groundwater level is approximately 0.1 meters per year, a scenario of reducing extraction from all operating wells has been applied to balance the aquifer. With a 5% reduction in extraction, the aquifer is projected to experience a half-meter increase in the static level. The Miandoab aquifer, due to the low slope of the plain, is sensitive and shows a part of the plain as a water ponding in reducing extraction at a high rate, hence any policy-making should be based on modeling. To improve the conditions of the Miandoab aquifer, one of the country’s most unique aquifers, suggestions have been made for changes in the cultivation pattern of agricultural products, monitoring of water extraction from operating wells, and examination of the impact of climate change and drought on groundwater resources in terms of quantity and quality. Various scenarios, including optimization and change of cultivation pattern, as well as the construction of drainage in areas where evaporation from the aquifer is high, should be evaluated to improve the aquifer situation.

Runoff is the main variable for the hydrological analysis of the watershed, and due to its importance, for several decades, hydrological research has focused on the simulation of rainfall-runoff relationships, which has led to the presentation of many models. Due to the multiplicity of hydrological models, choosing an optimal model among various models is not a simple process. For this purpose, in the present research, after selecting the Galikash watershed from the most flood-prone basins in Golestan province, the performance of three hydrological models AWBM, Tank, and IHACRES were evaluated and the parameters of the models were also analyzed for sensitivity and finally the efficiency of the models in wet and dry periods was examined. The amount of daily runoff from the watershed for a period of 30 years (1989-2019) was simulated using each of the mentioned models and using four criteria Nash-Sutcliffe evaluation coefficient, root mean square error, coefficient of determination, and mean absolute percentage error, the performance of each model has been checked in two periods of calibration and validation. After optimizing the values of all the parameters, the sensitivity of the parameters of each model has been analyzed. Finally, after specifying the drought condition with the SPI index, the performance of each model for two wet and dry periods has been investigated and evaluated. The results indicate that two rainfall-runoff models, IHACRES and AWBM, have almost similar performance. IHACRES model with Nash-Sutcliffe coefficients of 0.73 and 0.75 and RMSE of 2.97 and 2.94, respectively, in two calibration and validation periods and AWBM model with Nash-Sutcliffe coefficients of 0.74 and 0.69 and RMSE of 2.92 and 3.24 for the calibration and validation periods have shown good performance, but the Tank model was not successful in simulating the watershed runoff and its performance is lower than the two other models. The sensitivity analysis of the model parameters also showed that Kbase, H11, and f parameters are the most sensitive to the change of their values in AWBM, Tank, and IHACRES models, respectively. Finally, the comparison of the performance of the models in wet and dry periods showed that all the models have succeeded in simulating the watershed runoff with high accuracy in the wet period, so that the Nash-Sutcliffe coefficient is 0.79, 0.74 and 0.78 for the three AWBM, Tank and IHACRES models, respectively, shows the acceptable performance of the models in simulating the runoff in wet period. While the evaluation of the results has shown the poor performance of all models in dry period, and the Nash-Sutcliffe coefficient obtained for the models is -0.05, -0.45, and 0.12 respectively, which shows the weakness of the models in simulation of the low flow. In the evaluation of the three hydrological models AWBM, Tank, and IHACRES in daily runoff simulation, it was found that in general, with a small difference, the IHACRES model shows better results than the AWBM model. Also, in wet periods, according to the evaluations, the AWBM model led to good accuracy, while the IHACRES model has shown better performance than other models in dry period. Considering this issue, it can be said that the models performed weaker in simulating low flows that occur during dry periods, while the knowledge of streamflow conditions during dry periods can play an effective role in managing water resources. Therefore, to increase their accuracy, a solution should be found.

Arsenic, one of the most critical environmental toxins, accumulates in plant and animal organs through root absorption in plants and subsequent ingestion by humans via the food chain or direct consumption of contaminated water. Reports have highlighted the contamination of regional drinking water sources in Bijar city, Kurdistan province, with arsenic and its adverse effects on local residents. Therefore, this research aimed to investigate the distribution of arsenic in the water and soil sources of the region and evaluate the capacity of native pasture plants to absorb and accumulate this element.

Arsenic concentrations were measured in surface and subsurface waters of a 360 km2 region using the atomic absorption-graphite furnace method. The distribution of arsenic in the contaminated area was mapped using the ArcGIS program. Three sampling areas with varying pollution intensities (A > B > C) were selected. Soil samples and aerial parts of 13 plant species were collected and analyzed for arsenic concentrations, enabling a comparison of different plant species' ability to absorb arsenic.

The intensity of arsenic contamination in surface water, soil, and plants studied in this research exceeded typical concentrations of arsenic in water, soil, and plant sources. Total arsenic concentrations in water samples ranged from 4.5 to 280 μg l-1 and correlated with electrical conductivity, total dissolved solids, and total hardness (p < 0.001). Arsenic concentration in the soil of area A (Ali-Abad village) exceeded 2059 μg g-1 of dry soil, with contamination decreasing with distance from area A. A high correlation was observed between the intensity of water and soil pollution (R2=0.84). Arsenic concentrations in the aerial parts of 13 plant species with three replications varied depending on the plant species and the intensity of soil contamination (0 to 47.8 μg g-1). The intensity of soil contamination was on average 27.66 times higher than the amount of arsenic accumulated in the plant, indicating the high resistance of native pasture plants in the region to arsenic toxicity.

Field monitoring revealed that 45% of water resources in the sampling areas exceeded the national drinking water standard for arsenic (50 μg l-1), reaching 78% according to the World Health Organization standard (10 μg l-1). Concentrations of parent materials containing arsenic compounds were higher in areas A and B than in area C, with decreasing concentrations further from area A. The sampling region significantly influenced the average arsenic concentration in water and soil samples (P < 0.05). Arsenic uptake by the plant samples exceeded typical concentrations (0.1 to 3 μg g-1), with the highest mean arsenic concentrations found in the leaves of Astragalus bisulcatus, Chenopodium album, and Mentha longifolia, accumulating more than 47.8, 35.5, and 22.5 μg g-1, respectively. The study demonstrates heavy contamination of water, soil, and plant resources in the region, with most surface water resources utilized for agricultural irrigation, animal consumption, and occasionally drinking water for village residents. The entry of arsenic into the human body, directly or through the food cycle, poses a severe health risk to the region's residents, necessitating immediate intervention measures.

One of the natural structures in rivers is mid-channel bar that is created due to shear stress decreasing and sediment deposition in the central part of river. Bifurcation and erosion are seen in rivers because of mid-channel bar existence. Also, energy loss is the other impact of mid bars that would intensify the deposition in rivers. Mid-channel bar is known as one of the most important aquatic habitats, so there is necessity to find more information on flow structures around it in operation processes and river restoration. In this research, the flow structures around mid-channel bars are assessed as laboratory study. Three mid-channel bars were made in the shape of rhombic, ellipse and lemniscate in this research. These shapes are common in natural alluvial rivers. This study was established in a laboratory flume by length of 9 meter, and width and height of 0.4 meter. The bed slope was fixed of 0.0007. This flume was located in the water and sediment research laboratory in Gorgan University of agricultural sciences and natural resources. Three-dimensional velocity of flow was collected using an electromagnetic current velocity sensor with a frequency of 30 Hz in 39 data points. The flow discharge was fixed as 4.5 liter per seconds using a frequency flow meter. The flow regime was subcritical and turbulent in all examinations. Findings showed that bar shapes have different impacts on flow structures and amounts of energy losses. Comparison between plots implied that there are similar conditions in elliptical and lemniscate shapes but a little different in rhombic case. The variation range of transverse velocity was between 0.4 to 1.6 times of average value for all shapes. According to the results, the existence of elliptical bar led to significant tolerance in longitudinal velocity in all axes (between 0.5 to 1.6 times the average in left and right axes and 0.2 to 1.4 times the average value in central line), but these tolerances were not significant for lemniscate and rhombic bars (between 0.8 to 1.2 times the average value in left and right axes and between 0.8 to 1.4 times the average value for central axis). The variation of vertical velocity in middle axis presented the maximum decrease before facing elliptical bar and similar conditions for this axis in facing with lemniscate bar, except that this decrease is started exactly at facing point here. In addition to the values of the velocity components, the direct effect of encountering bars should also be sought on the values of the flow energy as a cumulative indicator of the erosive power of the flow. A more detailed analysis of the graphs shows left that in the and right axes, encountering the elliptical bar has led to an increase in the relative energy of the current by 1.4 times the average, and after passing through the bar, the energy load has decreased to less than the average value. But in the middle axis, the presence of the bar reduced the relative energy of the flow to 0.6 average value and after passing through the bar, this component has an increasing trend. Exposure to the elliptical bar led to the greatest changes in the relative values of the triple velocity components, compared to the rhombic and lemniscate bars. Also, the changes in the total energy load caused by the presence of two rhombic and lemniscate bars are insignificant, but similar to the changes in all three velocity components, transverse, longitudinal, and vertical, the elliptical bar led to significant changes in the relative values of the total energy load along the channel.

Soil salinization is known as one of the most important reasons for soil degradation in arid and semi-arid regions, which leads to a decrease in the stability of the soil, soil fertility, and plant production, and increased dust emission. However, the use of soil microorganisms as soil inoculants improves the quantitative and qualitative components of the soil. As well as, their role in soil erosion controlling and soil management has been approved, but their success in creating biocrusts in soils with high salinity has not been considered. Therefore, this study was planned to evaluate the cyanobacteria inoculum capability for biocrust formation in the high salinity soils of the dried-up beds of Lake Urmia at laboratory conditions.

In November 2022, the soil samples were randomly taken from 10 cm above the ground in the Seporghan area, west of Lake Urmia, and transported to the laboratory of the Faculty of Natural Resources of Urmia University and kept at 4 °C. Then, the experiment trays with dimensions of 5x10x15 cm were filled with saline soil (EC= 27 dS m-1); which was taken from the dried-up beds of the west of Lake Urmia. Afterward, 225 mg of the dominant and native cyanobacteria (Nostoc sp. and Oscillatoria sp.) were identified, extracted, purified, and proliferated from the study was water-inoculated uniformly on the soil surface of each tray (or any experimental unit with an area of 0.15 m2) with three replications. On the other hand, for control treatment, the distilled water (without cyanobacteria biomass) was sprayed on the soil. After 120 days, the important indicators of the soil biocrust, such as the chlorophyll-a content, polysaccharide concentration, and activity indicators of L and a components were measured to evaluate the cyanobacteria biocrusting capability. Statistical analysis of data was done in SPSS 23 software.

The results showed that the inoculation of cyanobacteria affected the biocrust development in a high saline soil; in such a way that the cyanobacteria led to a 53.92% increase in soil chlorophyll-a compared to the control treatment. The L and a in the inoculated treatment also decreased by 21.80% and increased by 73.35%, respectively, in compared to the control, these results show the change in soil surface color to darkening and green due to the increases of cyanobacteria biomass. The L and a values confirmed the growth and activity of cyanobacteria in saline soils.

Finally, we found that cyanobacteria can grow in high-saline soils, and it is possible to propose the inoculation of cyanobacteria as a bio-based strategy. This approach is known in line with the soil conservation goals in the biocrust formation of saline soils to prevent the spread of erosion.

The wind, as one of the most effective factors on evaporation from the surface of water sources, such as reservoirs of dams, plays a significant role in estimating the volume of losses due to evaporation and thus protecting water resources. However, in most evaporation estimation methods, such as experimental relationships, evaporation pans, and even new methods such as the use of satellite images, wind is considered as a constant parameter. The wind parameter has a spatial distribution under the influence of the elevations overlooking the lake and water levels. On the other hand, simulating the spatial changes of the wind and investigating its effect on evaporation, as one of the factors affecting the water cycle, is time-consuming and difficult due to the complexity of the calculations. Failure to apply wind location changes will reduce the accuracy of the calculated evaporation and as a result, it will be difficult to access the exact amount of evaporation losses.

In this study, to calculate the effect of spatial changes of wind on evaporation losses from the Dez Dam reservoir located in Khuzestan province and the southwest of Iran, the combination of the CE-QUAL-W2 model and Bowen Ratio Energy Budget (BREB) method was used. The wind shelter coefficient (WSC) as one of the input parameters to the CE-QUAL-W2 model, makes it possible for the model to consider the wind shelter condition in different segments of water bodies differently. However, due to the lack of access to a suitable criterion to show the wind shelter condition in different segments, before this research, the value of WSC was considered constant in all or large parts of the water body. In this study, CE-QUAL-W2 model capability was used for reservoir segmentation, and wind shelter condition was determined in each segment, using the wind shelter index (Sx). Therefore, it was possible to assign different WSC values in each segment. In this way, the thermal profiles in each of these segments, under the influence of two conditions of constant and variable wind (constant and variable WSC), were extracted and entered into the BREB method to calculate evaporation.

The results showed that the application of spatial wind changes compared to constant wind conditions, improved the performance of the CE-QUAL-W2 model by 45% in the temperature calibration stage. Also, the monthly evaporation from the lake increased by 13%.

This study, introduced a standardized method for simulating the effect of spatial wind changes on evaporation from water surfaces. So that, it was possible to quantify the effect of wind on evaporation and as a result water losses from the lake, by comparing two conditions of variable and constant wind, in different segments of the studied lake.

The use of fossil fuels and land use change has caused a catastrophic increase in carbon in the atmosphere, which has led to a decrease in soil quality, global warming, and climate change. The deficiency of organic matter, salinity and alkalinity of the soil are three important limitations of the soils of winter rangelands in Iran. Biochar is a carbon-rich material that is produced during the pyrolysis process from raw materials containing carbon at high temperature and under almost oxygen-free conditions. It is used to improve soil quality, carbon sequestration and remove pollutants from the environment. Biochar can be engineered/designed for specific applications or to achieve specific results. Increasing the percentage of stable carbon and improving the physico-chemical properties of engineered biochars can play an important role in carbon sequestration and improving the properties of winter rangelands soils. After washing and drying, the cotton stalk was cut into pieces of less than 2 cm. Then it was immersed for 4 hours in a solution with a concentration of 20% metal salts of calcium chloride, magnesium chloride and iron chloride, and dried again. Then, in the electric furnace, at various temperatures of 300, 400, 500, 600 and 700 degrees centigrade, within two hours, 20 biochars (control and engineered ) were produced from treated cotton stalks with different metal salts and untreated cotton stalks. Finally, properties of produced biochars including yield percent, organic carbon percentage, stable carbon percentage, acidity and salinity were measured. Statistical analysis was performed in SPSS16 software using one-way analysis of variance and Tukey's test. The yield of produced biochars (control and engineered) significantly decreased with increasing temperature, so that the highest percentage of their yield was observed at pyrolysis temperatures of 300 °C. The highest percentage of yield (50.20%) was obtained in biochar treated with iron chloride produced at 300°C. The highest organic carbon (50.97%) and stable carbon (99.57%) were obtained in control biochar produced at 500°C and biochar treated with iron chloride produced at 700°C, respectively. The highest increase in the ratio of the weight of stable carbon to the weight of the feed stock was observed in biochar treated with iron chloride produced at 300 °C. The lowest and highest electrical conductivity (1.1 and 7.43 dSm) were obtained in control biochar produced at 300°C and calcium chloride treated biochar produced at 700°C. The highest and lowest acidity (9.83 and 5.60) were observed in control biochar produced at 700°C and iron chloride treated biochar produced at 300°C. Considering the limitations in the soil of Iran's winter rangelands and the characteristics of control and engineered biochars along with the energy required for their production, Biochar produced from cotton stalks treated with iron chloride salt at 300°C has the highest performance and high stable carbon, the lowest acidity and acceptable electrical conductivity, therefore, it is recommended to use in carbon sequestration and plantation projects in winter rangelands of Iran.