نشریه دانش آب و خاک
سال سی و سوم شماره 2 (تابستان 1402)

The use of biochar as an amendment in soils contaminated with heavy metals is an economical and environmentally-friendly method. The biochar's effectiveness in heavy metals stabilization is related to the biochar and soil properties. Success of biochar application is related to determining the most important characteristics of biochar that increase effectiveness of biochar. It is not easy to use a wide range of characteristics in a study, therefore the most appropriate results are obtained by analysis the results from different studies. Meta-analysis is the application of statistical techniques to combine and summarize the findings of multiple studies. By combining data from many studies, meta-analyses can provide more precise information about biochar. Therefore, in the present study, the effectiveness of biochar for remediation of heavy metal contaminated soils in Iran has been studied by meta-analysis and the most important factors were determined.

The articles were selected from various databases based on keywords such as bioavailability, various heavy metals forms, biochar, remediation of contaminated soils, heavy metals stabilization, in the of period 2016-2020. The data were extracted from results of 30 articles. Finally, the required information was collected from 11 articles and 123 independent observations. In these studies, the evaluation of heavy metals bioavailability was carried out with different methods, such as mobility, leaching, adsorption kinetics, plants bioavailability and heavy metals bioavailability in soil.  In order to determine the effectiveness of biochar, the size effect variable (R) was estimated for the bioavailability differences between the control and treatment groups. Due to, there were different methods for assessing the biochar effectiveness, in this study, the biochar effectiveness was calculated by obtained information from bioavailability studies. Also, Spearman correlation test was used to examine the relationships between variables. Statistical analysis was performed using SPSS and Excel software. Also, Web Plot Digitizer software was used to extract data from the presented graphs in the articles.

Based on the results from most studies, agricultural wastes were used as the raw materials for biochar production. In these studies, the treatments such as temperature, pyrolysis time, weight percent of biochar in soil, and incubation time were used. The weight percent of biochar in soil was more considered than other treatments by researchers. In the case of soil, variables such as pH, EC, CEC, CCE, soil texture, organic matter were more considered than other physical and chemical properties. There was a statistically significant difference between the studied heavy metals in terms of R variable (p <0.05). According to the results from studies, biochar was more effective in decreasing the bioavailability of soil lead. Also biochar was most effective in reducing the bioavailability of zinc and cadmium. Effectiveness of biochar had significant positive correlation with biochar pH, application rate in soil, incubation time, pyrolysis temperature and carbon content of biochar, the amount of silt and clay in soil, soil EC, soil CEC and soil organic matter but significant negative correlation with biochar EC, amount of sand and soil pH. The highest correlation coefficient (0.515) was found for soil CEC. Therefore, this factor was the most important factors influencing the effectiveness of biochar in stabilization of heavy metals.

In Iran, agricultural wastes have higher priority for biochar production, because the high rate of waste prodution in agriculture. On the other hand, there are processing problems for other raw materials, including the high concentration of heavy metals in wastewater, high cost and need for advanced equipment to obtaion a secure biochar for application in the soil. Based on the obtained results, biochar is effective in stabilizing heavy metals in contaminated soils and in this regard, there is a positive or negative relationship between soil properties and biochar. Therefore, it seems that by improving some factors that have a positive correlation, the effectiveness of the biochar can be increased, and for some characteristics that have a negative correlation, the effectiveness of the biochar can be improved by modifying them. In these studies, the long-term effects and security of biochar applications for soil remediation, soil organisms, and plant growth need to be considered.

Gradual decline in water resources require suitable management of irrigation water and applying of deficit irrigation.Field tests to analysis of different states of deficit irrigation are constrained due to restriction of the experiment reliability to the physical conditions of the test place and limited number of the testing scenario in field and the high cost of testing.To overcome these limitations, crop models can be used as a powerful tool to simulate field tests.In this research, AquaCrop model was evaluated in deficit irrigation of winter wheat in Zanajn Region.The study data was collected from filed test values which was done in Research Farm of University of Zanjan at2010-2011.The filed test was carried out to assess reaction of winter wheat to deficit irrigation treatments.The test was done as split plot design on the base of complete randomized block.Irrigation treatments were done as supplying of100%,80%and60%of crop water requirement.The first replication data was used for model calibrating.By entering harvest index data of the second and third replications data of irrigation treatment to model.their yield and water use efficiency were simulated.On the result, the highest difference between simulated and recorded data of yield and water use efficiency were as6.9%and7.0%(respectively)at the third replication of 80%crop water requirement treatment.The least difference were as1.0%and0.5%(respectively)at the second replication of60%and80%crop water requirement treatment(respectively).R2of simulated and real data was calculated0.96for yield and0.99for water use efficiency.High value ofR2data was demonstrated suitable performance of AquaCrop model in simulation and forecasting of yield and water use efficiency of winter wheat in deficit irrigation condition.

The gradual increase in the world’s population requires continues increase in agricultural production. Climate change is one of the challenges of our society and frequent droughts affect large areas of the world, which requires more accurate management of water resources, both globally and in local catchments. Accurate estimation of components of the hydrological cycle is essential for proper irrigation scheduling. Most of the precipitation received by the earth is returned to the earth’s atmosphere by the process of evapotranspiration. On the other hand, because every process that takes place in the plant is dependent on water and one of the most common uses of water in the plant is evapotranspiration, so reducing amount of the water will have adverse effects on photosynthesis, crop production, product quality, etc. The complex and nonlinear relationship between the factors affecting the process of evapotranspiration, has caused researchers today to use new methods to accurately identify and predict this parameter. Reference evapotranspiration is a concept that uses the crop coefficient to obtain the actual water requirement. According to the FAO proposal, the FAO- Penman- Monteith equation was introduced as a benchmark method for calculating reference evapotranspiration values when measurements of this parameter are not available and there is no access to lysimetric data. One of the major advantages of this model is its physical basis and global validity, but this equation needs a large number of meteorological parameters that are often not available, instead empirical equations with low meteorological variables or modern methods such as artificial intelligence and machine learning methods can be used.

In this study, meteorological data related to two stations of Astara located in the humid region and Sirjan located in the arid region of Iran in the period of 2000-2020 were studied to predict the crop evapotranspiration values. As mentioned, the FAO- Penman- Monteith method has used as a standard method for calibration and evaluation of the other functional equations and machine learning methods. In this study, four types of empirical equations including Hargreaves –Samani, Makkink, Turk and Dalton were evaluated against the FAO- Penman- Monteith model. Also, modelling was performed using Support Vector Regression, Random forest and M5P Tree model. In this study, 70% of data were considered for training and 30% for testing. Finally, statistical parameters including root mean squared error (RMSE), correlation coefficient (R), scatter index (SI), Nash-Sutcliffe coefficient (NS) and Wilmot index (WI) were used to determine the performance of each mentioned methods in estimating reference evapotranspiration values.

Using different meteorological parameters in accurate prediction of evapotranspiration using 4 combined scenarios, calibration calculations were performed on 70% of data and validation calculations were performed on 30% of testing data implementing Weka software. The obtained results showed that the SVR3 and M5P3 models in Astara station with all meteorological parameters and having R= 0.993, RMSE= 0.201 and also, the SVR3 model in Sirjan station with R= 0.982, RMSE= 0.410 compared to the studied empirical methods provided better results in estimating the reference evapotranspiration and scenario 3 with all meteorological parameters was introduced as the top scenario. Among the empirical methods, Hargreaves- Samani was superior to some models only in Astara station. At Sirjan station, none of the empirical models performed better than the machine methods.

Accurate estimation of reference evapotranspiration in water resource management is essential. In this study, meteorological data from Astara and Sirjan stations were used to evaluate the ability of machine learning methods including SVR, RF and M5P to estimate the values of reference evapotranspiration and compared the results with empirical methods. The results showed that the high accuracy of the SVR3 model in both stations and in the next position M5P3 model for humid area. Empirical methods except Hargreaves- Samani had poor performance compared to data- driven models. Finally, the use of SVR and M5P methods in irrigation scheduling is recommended.

Petroleum contamination is treated by physical, chemical and biological approaches. The first two methods have limitations such as high costs, inefficacy and altering natural ecosystem. Today, biological treatment is a more interesting process to remove petroleum contamination. Bioremediation is a technique in which biological systems such as microorganisms are applied to destroy or transform (degrade) harmful chemicals. In recent years, employing hydrocarbon degrading bacteria to clean a petroleum contaminated soil has become a prevalent, efficient and economical technique that converts toxic wastes to non-toxic end products. This technique has reduced the harmful effects on health and ecology. Soil contamination with petroleum compounds such as heavy naphtha can threaten soil, environmental and human health. In bioremediation process, soil microorganisms use these hydrocarbons as a carbon source and, while making a microbial biomass, play a role in its decomposition and conversion to carbon dioxide. Bioremediation methods include biostimulation and bioaugmentation, which are promising methods for treating oil pollution. Application and comparison of various bioremediation methods such as biostimulation, bioaugmentation and integrated treatment was the main aim of this study to bio-remove heavy naphtha from contaminated soil. For this purpose, in a heavy naphtha-contaminated sandy loam, a variety of bioremediation treatments, including biostimulation (including supply of nitrogen-phosphorus elements, addition of manure and Tween 80 surfactant), bioaugmentation treatment (using a consortium of efficient bacteria) and integrated treatment (including all biostimulation and bioaugmentation treatments) were tested.

In this experiment, sandy loam soil was used. Heavy naphtha contamination was applied at a rate of 7% in soil samples and various bioremediation treatments were performed as mentioned above. This experiment was carried out in a pot scale (3 kg pots) based on split plot factorial design (pollution factor, bioremediation factor and time) with 3 replications, at room temperature for 120 days. During the experiment, the pots were aerated once a week and the soil moisture content was adjusted to 70-80% of the soil water holding capacity twice a week. For bioaugmentation of bacterial isolates, a consortium of Arthrobacter sp. COD2-3, Stenotrophomonas nitritireducens COD5-6، Stenotrophomonas asidamainiphila COD1-1 with a ratio of 5% V/W were used. In biostimulation treatment, cow manure with 5% W/W ratio was used. In NP treatment, which was related to the supply of nitrogen and phosphorus elements, N and P elements from sources of ammonium nitrate and potassium phosphate with a ratio of 20:5:1 (C: N: P) were used. Also, to use Tween 80 surfactant in the relevant treatments, a rate of 0.3% V/W was used. In the integrated treatment, all the mentioned treatments were used together to remediate oil contamination. On days 0, 5, 10, 15, 30, 45, 60, 90 and 120, samples were taken from each pot to measure the biological activity of basal respiration (BR) and substrarte-induced respiration (SIR).

The results showed that the bioremediation treatments reduced heavy naphtha contamination. Contamination also affected soil microbial activity, so that BR and SIR increased in all bioremediation treatments in the early days, but over time they decreased, due to the reduction of carbon source and also the reduction of soil nutrients. The amount of BR and SIR in the combined treatment changed from 0.67 to 0.53 and 3.30 to 2.73 (mg CO2 g-1 h-1), respectively. Also, the amount of petroleum compounds before and after bioremediation treatments showed that 81% of heavy naphtha was decomposed by the integrated treatment. Among the bioremediation treatments, the integrated treatment had a greater effect on the elimination of heavy naphtha contamination than the biostimulation and bioaugmentation treatments (p <0.01). The use of integrated methods not only increases the active population of microorganisms in the decomposition of petroleum compounds and provides optimal conditions for their activity, but also stimulates the native population of microorganisms and is convenient for removing petroleum compounds. It seems to be a good method.

According to the microbial respiration results in naphtha-contaminated soil, each treatment was able to reduce contamination on its own, while the integrated treatment was biostimulatory and bioenhancing treatment. However, in the integrated treatment, the efficiency of bioremediation process was higher, due to the simultaneous use of biostimulation and bioaugmentation treatments. The use of integrated treatment in places contaminated with petroleum compounds, including heavy naphtha, can help to biologically eliminate these contaminants.

Previous researches show that the situation of underground water tables in Iran is dire. Therefore, it is necessary to make changes in the current management of water resources. Also, in the discussions related to the application of water resource management options, the effect of climate change and its related uncertainty have either not been considered or have been rarely considered. The aim of this research was to management of underground water resources of Qom-Kahak aquifer under different options. First, the groundwater flow of the study area was simulated and calibrated using GMS software. Then, 10 management options were applied to the model considering the effects of climate change and without considering these effects, and the aquifer balance status was investigated under the effect of these management options. In order to obtain a suitable solution to balance the water of aquifers, the implementation of this research can be of great help to water resource managers and planners.

In this study, using GCM and GMS models, climatic variables and Qom-Kahak aquifer were simulated and calibrated in a 16-year observation period (2001-2007). Ten different management options, (1) 15% increase in withdrawal without climate change, (2) 15% increase in harvest withdrawal in terms of climate change (HadCM3-A2), (3) 15% increase in withdrawal in terms of climate change (Hybrid-A2), (4) 15% increase in withdrawal in terms of climate change (HadCM3-B2), (5) 15% increase in withdrawal in terms of climate change (Hybrid-B2), (6) 15% decrease in withdrawal in terms of climate change, (7) 15% decrease in withdrawal in terms of climate change (HadCM3-A2), (8) 15% reduction in withdrawal in terms of climate change (Hybrid-A2), (9) 15% decrease in withdrawal in terms of climate change (HadCM3-B2), (10) 15% reduction in withdrawal in terms of climate change (Hybrid-B2), was defined and the effects of their application on groundwater level were analyzed.

The results obtained from the application of the management options of 15% increase in harvesting due to the effects of climate change by the developed Hybrid model and the HadCM3 model showed that the reduction of the underground water level under the A2 scenario is more than the reduction of the level obtained under the B2 scenario. Also, by applying the management options of 15% reduction in harvesting due to the effects of climate change, it was determined that the increase in the aquifer level under the A2 scenario is less than the increase in the level under the B2 scenario. This issue is due to the lower predicted rainfall of these models under the A2 emission scenario. Finally, after examining the results of applying the management option without the effects of climate change and assuming the continuation of the current rainfall trend, it was found that with a 15% reduction in harvesting, the increase in water level is more than other options, and by increasing this amount of harvesting, the reduction in water level is less than that of other options. As a result, it can be concluded that among the management options presented in this research, the options of increasing and decreasing the harvest by 15% without considering the effects of climate change are the best management options and the results indicate a positive reaction of the aquifer to this management option, and in contrast to the management option of increasing and harvest reduction in terms of climate change effects by the developed Hybrid model and the HadCM3 model under the A2 scenario are the worst options.

Using the results of these management options, researchers and users of the Qom-Kahak aquifer can understand the effects of reducing and increasing harvesting and take the necessary solutions and decisions to prevent possible losses. According to the obtained results, applying the option of reducing the harvest by only 15% can be considered as a suitable management solution to improve the situation of the Qom-Kahak aquifer. There are solutions to reduce harvesting in the area, which can be mentioned saving and optimal water consumption in the agricultural sector, preventing the harvesting of unauthorized wells and preventing the digging of new wells, artificial recharge of the aquifer through the drilling of injection wells, continuous monitoring of water consumption, making managers and operators aware of the value of underground water resources, using the results of research conducted in the field of water resources management and cultural works such as making people aware of the value of water through national media, including materials in the field of students' awareness to prevent water wastage, preventing water contamination, etc.In this research, in order to manage the Qom-Kahak aquifer, the underground water flow was first simulated and calibrated using the GMS model during the observation period (2001-2017). Then, with the aim of improving the condition of the aquifer, different management options of crop change without the effect of climate change and considering these effects were evaluated. The results of applying these management options showed the high importance of harvesting on the water level situation in the future periods. Because after applying the management option of 15% reduction in harvest due to climate change and decrease in rainfall, the underground water level in all observation wells increased.

Detection of trends in streamflow characteristics such as low flows is so important in optimal water resources management. This is especially true in arid and semi-arid climates that water is vital for human being and all other living things. Lorestan province, located in the west part of Iran was considered as the study area. Daily mean streamflow data of hydrometric stations during the time period provided by Lorestan Regional Water Company located in Khorramabad city. Eight hydrometric stations selected for this purpose. The altitude of the chosen stations varied between 770 and 2050 m above the mean sea level. Literature review on this subject indicated that low flow trends in Lorestan province river has not been before studied. On the other hand, such a study is so important for better management of fresh water in the region, therefore, conducting this study seems to be necessary.

In the first step of this study, flow duration curves (FDC) plotted for the stations. Two indices including the Q0.05 and Q0.10 were considered here as measures of low flows. The Q0.05 index value extracted from the FDC as a five percent low flow quantile. This index shows that the streamflow discharge is less than that in five percent of the days in a year. In addition to Q0.05 the second measure namely Q0.10 is read from FDC of the selected sites. Therefore, for each site, these two indices were gathered during the used time period. Then, trends of the mentioned indices are analyzed using the Mann-Kendall method. In this regard the effect of serial correlations removed from the time series. Moreover, the slope of trend lines estimated using the Sen’s estimator approach. Then the selected quantiles fitted for suitable statistical distributions. In this regard the well-known method namely Kolmogorov—Smirnov was used.The parameters of the selected distribution estimated using the maximum likelihood method. Finally, at each site the values of low flows corresponding to different return periods i.e. 2, 5, 10, 25 and 50 years were estimated. It is worthy to mention that the missing data are not reconstructed here, because the used approach (Mann-Kendall) is a non-parametric method and no need for reconstruction of the missed values.

Results showed that two stations namely Sokaneh-Nahaee and Cham-Chit had significant first-lag serial correlation for Q010 time series. The other six sites had no significant serial correlation for this quantile. Furthermore, in the case of Q0.05, three sites showed significant first-lag serial correlations. So, the modified Mann-Kendall method was used for these time series. This analysis indicated that the mentioned series auto-correlation was significant in 5% level. The conventional MK method was used to detect trends in other time series which their serial correlations are not significant. Results showed that trends of Q0.10 quantile series in four out of the eight hydrometric stations were downward and two of them were statistically significant at 1% level. The two others had no significant trends. At the same time the other sites showed upward trends in Q0.10 series. However, among these series one station namely Cham-Chit had statistically upward trend at 1% level. Trends in the other three sites are not statistically significant.  In the case of Q0.05 series, the six out of the eight stations showed negative trends, in which two sites had statistically significant trends at 1% level. The names of these sites are Sokaneh-Nahaee and Vanaee. In contrast, the two other time series showed positive trends, in which only one of them (namely Cham-Chit station) had statistically significant trend at 1% level. The trend line slopes of Q0.10 quantile time series are ranged between -0.0844 (in Sokaneh-Nahaee) and +0.12 (in Cham-Chit). However, in the case of Q0.05, this range was between -0.0885 (in Sokaneh-Nahaee) and +0.008 (in Cham-Chit station).

Some of the stations showed upward trends in low flows in Lorestan province rivers and some others showed downward trends. It is worthy to note that the time periods of the used data of the stations are not same. Although Masih et al. (2011) reported that the mean daily stream flows (i.e. Q0.50 or 50th quantile also called median) of Zagros Mountain rivers had downward trends. Investigation of sites location indicated that no obvious pattern in trends of low flows existed in the area under studied. This is true for both two low flow indices (i.e. Q0.05 and Q0.10) used for hydrometric stations. The findings of this study would be helpful in better management of surface water in Lorestan province.

Surface runoff and water flow in rivers cause soil erosion and carry sediment materials. Knowledge of how erosion and the ability to carry sediment in rivers and waterways should be considered in every engineering plan. One of the most important factors in disrupting the hydraulic balance of the river is the indiscriminate removal of sediments from the river bed. Today, the materials obtained from rivers are very vital in human life, especially in civil and industrial activities, and are of great importance. Indiscriminate and out-of-capacity harvesting of sand causes changes in the morphology of rivers, which results in the river's reaction to establish a new balance. The study of past research indicates that sand harvesting has caused different changes in the hydraulic pattern of rivers, changes in morphology, and changes in the sediment balance of rivers. The extraction of sand from the country's river beds has increased in recent years. Due to the complexity of hydraulic and sediment problems in rivers, it is not possible to solve the equations analytically, hence numerical methods are usually used. Various studies have been conducted using the HEC-RAS model to investigate the flow of hydraulics in the river. Various researchers in the country have also used this model to investigate sediment transfer in rivers and reservoirs of dams.

In this research, a part of the Khara River located in Khandab City, which is subject to excessive sand harvesting, was investigated. In this study, HEC-RAS 5.3 model was used to simulate sediment flow. For Joshirvan hydrometric station, discharge was calculated with a return period of 2, 5, 25, 50, and 100 years and used for hydraulic simulation of the river. To use the HEC-RAS model for hydraulic simulation of flow and sediment, river information including geometric data, hydraulic data, and sediment data was used. In the geometric section, the general plan of the river along with cross sections was introduced to the model. Using the topographical map of the river course in two time periods before sand and sand harvesting (2015) and after sand and sand harvesting (2017), a digital elevation model of the Kurkhane river course with a scale of 1:2000 was prepared for both periods. Then, a TIN was made from the prepared digital elevation model, and 200 sections were extracted in the HEC-GeoRAS add-on package in the Arc Map software along the length of 3.5 km of the river. After preparing cross-sections and measuring the distances of the left and right banks of the main channel of the river, the relevant information was connected to the HEC-RAS model in the form of a GIS file to introduce the geometry of the river. Finally, the changes made in the geometry and morphology of the river were compared by examining the parameters before and after harvesting the materials and field investigations in the periods when this operation was carried out.

By comparing the longitudinal profile of the bed in the post-harvest conditions compared to the pre-harvest conditions, it was found that in the first half of the studied interval from the upstream side (section 1-98) a sedimentation phenomenon occurred with a shallow depth, while in the middle half of the studied interval study (section 100-150) there has been an uplift of the river bottom. The results showed that the amount of erosion and sedimentation in the first 1.5 km and the last 1 km is almost low, and the materials in this area are not very removable. The best area for collecting materials in this interval from 1.5 to 2.5 km is almost in the middle of the interval. According to the changes in the river bed, the maximum change is about 1.2 meters and the average changes are about 0.5 meters along the river path.

Results showed that the rate of erosion and sedimentation in the first 1.5 km and the last 1 km almost decreased in the sedimentation state and the materials in this area are not very harvestable. The best area for harvesting materials in this range is from 1.5 to 2.5 km approximately in the middle of the range. Due to the slope and cross-sectional shape, the flow velocity has decreased and sedimentation with an average depth of 1.2 meters has been done. Calculations showed that the amount of sediment that can be removed from the river in this period is about 200 tons per year.

Iran’s groundwater resources are considered as a vital water supply for a number of reasons, and inconsiderate usage and exhausting these vital resources would bring about a severe water crisis in the country. Underground waters are usually consumed for different purposes ranging from drinking and agriculture to industry, so that the quality measures of these resources depend on the main purpose that they are intended to be used. Consequently, different standards of quality restrict the water consumption in order to reduce harmful effects of them. Furthermore, Water quality is generally an extremely important subject in water studies, and identifying and analyzing the chemical compounds in groundwater resources could be beneficial in agricultural studies. In agriculture, both water quality and quantity play 2 part, and poor quality could certainly become a primary restricting factor in water usage. This can cause undeniable farming problems and could damage the soil as well. In this regard, the necessity of providing a proper, well-planned management system for monitoring and controlling water quality is of a great importance.Over the past years, in many parts of Iran, including Jiroft, in which this study is carried out, because of some important issues such as the growing population, frequent periods of drought and inconsiderate using of the dwindling supply of groundwater, the quality and quantity of these waters are rapidly diminishing. As the livelihood of a huge number of local people who lives in the region of Jiroft, depends on agriculture, the effective management of these water resources needs better and more up-to-date information about these resources. Having such data could definitely help us to be aware of recent changes and to be able to make better, informed decisions. The main purpose of this study would be analyzing the changes of chemical parameters in underground waters of Jiroft plain.

 Hydro-chemical analysis of Jiroft’s groundwater resources for agricultural consumption is our primary goal in this research. In order to achieve this goal, we gauged and analyzed different chemical parameters including electrical conductivity (EC), total soluble solids (TDS) and acidity (pH) in 30 samples of the wells with suitable dispersal in the region in the years of 2011 and 2018. To understand the spatial distribution of suitable areas, ArcGIS 10.5 software is used and the data layers were prepared.

 The results of the Wilcox diagram show that most of the samples are in class C2-S1, which is a sign of a low salinity line and therefore they are applicable in agriculture. Besides, a limited number of samples are in class C3-S1, C3-S2 and C4-S2, which have high salinity line and are consequently ideal for irrigating the plants that are not sensitive to salinity. It is noteworthy that none of the samples has a low salinity contamination (C1-S1). Considering the fact that most of the samples in the study area are in the range of C2-S1, they could be suitable for irrigation. According to the Wilcox diagram, the quality of agricultural water in the groundwater samples in Jiroft is in a good and mostly moderate category. Our research finding shows that TDS variations is between 320 and 2048 mgL-1, and pH variations is between 6.6 and 8.6, and therefore they are ideal for irrigation purposes.

 During the statistical period, the level of water reduction is increasing; although, in some years, the number is lower. These considerable changes confirm frequent droughts and a vast amount of underground water consumption. In this situation, diminishing groundwater quality would be inevitable and if this trend continues, the quality level of these waters will be reduced gradually. In the years when water level reduction is lower than others, we can see higher level of rainfalls or even floods in which took place in the region frequently in recent years. This naturally fuels Jiroft’s aquifers and decreases the level of water reduction. According to the zoning map of the distribution of groundwater quality parameters, the Jiroft plain has a suitable quality for agricultural purposes. Only in the southwestern margin and some other parts of the plain, the groundwater quality is lower and could not be suitable for farming purposes. Overall, most areas of the plain are of good quality and suitable for agriculture.

Water shortages in a defined area and in a certain period are called drought. This phenomenon is time dependent rather than aridity, and it is quitely temporary. drought in various regions of Iran in arid, semi-arid and even humid areas shows different forms and causes great damage. Drought is calculated using indices such as precipitation and evapotranspiration. The teleconnection is also a new branch of synoptic climatology, which recognizes the relationships between phenomena and climatic elements such as rainfall, drought, and temperature in remote locations. In other words, teleconnection patterns are the occurrence and continuation of large scale models of circulation abnormalities and air pressure that extend over a wide geographical range. These patterns are also oscillatory behavior of low frequencies. Teleconnection mechanisms are one of the important issues in justifying the behavior of the climate, and its effects do not always appear in the same form everywhere (Khosravi, 2004). In worldwide, many studies have been done on climate signals in variety ways. Iran is also affected by rainfall systems, which affects the pattern of rainfall and drought in it.

The purpose of this study was to investigate the relationship between NINO4 and NAO indices with meteorological droughts in synoptic stations in the southern part of the Caspian Sea. For this purpose, data of rainfall were obtained monthly from the Meteorological Organization of Iran. Then, SPI was calculated for different time scales of months including 1, 3, 6, 9, 12, 15, 18, 24, 48. The next step was to obtain the values of the Ocean Atmospheric indices, including NINO4 and NAO, at the monthly scale from the Australian Meteorological Organization. For analysis, the MINITAB16, SPSS16 was used. In this case, the simultaneous and asynchronous relationship between the time series of SPI and the NAO and NINO4 indices was determined. In this stage, Spearman's correlation test and cross-correlation function were determined. In the next step, regression modeling was done. In this way, regression models for the time series of SPI were calculated taking into the simultaneous and asynchronous state of the NAO and NINO4 indices. The lag times were 1-6, 12, 24, 48 months. Finally, errors for regression models were determined at all stations to select the best model.

The results showed relationships between NAO with SPI different series at Ardabil and Babolsar stations in January, April, August and December; the NINO4 with SPI at Ardebil station in all months except October and December. Also, the results of regression equations showed that in SPI time series of NINO4 with the highest coefficient, the highest and NAO with lowest coefficient, had the lowest effect on drought in studied areas. In this case, the Ardabil has the highest coefficient in SPI24 months. At the end, the error statistics including RMSE, R, R2, CE were calculated for model reliability and calculation of errors.

In this case, the best model was found at the Gorgan station by calculating the error statistics. The result suggests that these stations are neighbor to the Caspian Sea, which has affected the rainfall and drought pattern of the regions. This can also be the result of the universality of the Enso phenomenon that affects the world's climate. In order to obtain better results, it is recommended to study the precipitation and temperature pattern of these areas with other Ocean Atmospheric indices such as SOI and AO. Regarding the fact that the distant teleconnection indices do not occur in all directions in one way, it is suggested to study rainfall and temperature pattern of other parts of Iran in relation to climate signals. This study is also in line with another study by researchers who through statistical and synoptic methods have investigated the relationship between climatic factors such as rainfall and temperature with climatic signals. Study of other researchers determine that there is a significant relationship between the annual rainfall of Iran and the South Oscillation Index. temperature pattern of these areas with other Ocean Atmospheric indices such as SOI and AO. Regarding the fact that the distant teleconnection indices do not occur in all directions in one way, it is suggested to study rainfall and temperature pattern of other parts of Iran in relation to climate signals. This study is also in line with another study by researchers who through statistical and synoptic methods have investigated the relationship between climatic factors such as rainfall and temperature with climatic signals. Study of other researchers determine that there is a significant relationship between the annual rainfall of Iran and the South Oscillation Index.

Maize has special importance among cereals across the world, because it has many industrial applications in addition to food consumption. However, the production of this crop requires high amounts of water and fertilizers. The number of inputs will be increased in case of the limited lands are available for cultivation of this plant. Accordingly, land suitability for maize should be determined in order to find the best suitability classes for selection of lands with lower land limitations. The objective of this study was to investigate the effects of soil properties on grain yield of maize in order to determine different soil rating for suitability classes of Maize.

To achieve the objectives of this study, a total of 101 grain maize farms in Khuzestan, Kerman, Fars and Qazvin provinces were selected. A questionnaire form was completed for each farm. A soil pedon was also studied and some soil samples were taken to accomplish the related physicochemical analyses. After that, multivariate regression was performed simultaneously between yield as a dependent variable and different soil properties as independent variables. Subsequently, in order to modify an earlier version of soil and landscape requirement table, the simple regression analysis were performed to find the relationships between soil properties and maize yield for modyfing the rating classes of different land suitability classes. The available soil and landscape table for maize is based on a review of literature and experts opinion. Therefore, it was modified based on the collected data as well as the actual maize yield of farms in different regions of Iran. The verification of the proposed table was performed using data from 14 maize farms (about 14% of data) which was not used in the preparing the table. In the random selection of these 14 points, two samples from Fars, three samples from Qazvin, five samples from Kerman and four samples from Khuzestan were included.

Results indicated that the range of yield variation, lime, sand, clay, silt, exchangeable sodium percentage and soil salinity are high, but the percentage of organic carbon, soil pH and gravel percentage are distributed in a small range. In multivariate regression, the variables of salinity, exchangeable sodium percentage, sand percentage, organic carbon, soil pH, lime and gypsum contents were included, respectively. The coefficient of determination of the proposed relationship was about 0.83. Therefore, the variables entered in the model were able to explain about 83% of variance of the changes related to dependent variable. By using this equation, some simple soil properties can be used to estimate the maize yield. Using simple regression equations, the effect of each soil characteristic on yield was determined and with their help, the soil and landscape requirement table of maize was modified. The value of coefficient of determination between yield and soil index for the verification data was about 0.86, which indicates the reliability of the table proposed in this study. Comparison of this table with the proposed soil and landscape requirements table for maize presented by Sys et al. (1993) indicated that there are many differences in the boundaries of proportion classes for lime and gypsum variables. There is also a difference in the salinity and sodicity variability of the soil at the boundaries of classes S2, S3 and N.

Overall results of this study indicate that the main land limiting characteristics for maize production in the studied regions are soil salinity and sodicity. After these two variables, organic matter and soil pH are the main and effective factors influencing grain maize yield in selected farms across the country. In some areas, such as Kerman and Qazvin provinces, the physical properties of soil are limiting for maize cultivation and thus adversely affect reduction of the yield. As a consequence, it is clear that before planting any crop, the land suitability evaluation for any crop must first be assessed. By using the crop requirements table of each crop and land suitability evaluation one can recognize the land imitations of each region for cultivating that crop. Then, according to the type of limitationt, special management can be assigned for each region.

The gate is one of the hydraulic structures in which water passes through it. The most common types of these structures are sluice gates that move up and down in a vertical plane to adjust the opening. Estimating the discharge coefficient and consequently determining the flow rate under the gate is one of the basic and important issues in hydraulic engineering. Daneshfaraz et al. (2016) numerically investigated the effect of sluice gate edge shapes on flow characteristics. Their results showed that the flow contraction coefficient for sharp edges and round-edge gates decreases when the ratio of gate opening to upstream specific energy is less than 0.4 and increases for ratios greater than 0.4. The results of the research (Alhamid 1999) showed that the discharge coefficient increased in the sill mode compared to the no-sill mode. Salmasi and Abraham (2020) conducted an experimental study of sluice gate discharge coefficient with polygonal and non-polygonal sills. In the present study, general formula for calculating the flow rate under the sluice gate for the suppressed sill state has been developed for the non-suppressed sill and presented for the first time. The discharge coefficient was investigated in no-sill state at different openings and with the suppressed and non-suppressed sills in two openings in different positions relative to the sluice gate.

In this study, a laboratory flume with a rectangular cross-section of 5 meters long, 0.3 meters wide and 0.5 meters high with walls and floors made of transparent Plexiglas has been used for experiments. The experiments were performed in two states without sill at different gate openings and with sill at two openings. In this research, experiments using polyethylene sills with a thickness of 5 cm and a height of 3 cm in different widths of 2.5, 5, 7.5, 10, 15, 20, 25 and 30 cm was done at different positions relative to sluice gate. In total, 377 experiments were performed in the flow rate range of 150 to 850 L min-1

In without sill state, discharge coefficient is inversely related to the gate opening. Applying the sill below and tangentially to the gate leads to an increase in discharge coefficient. Also, with increasing the ratio of the upstream flow depth to the sill width, the discharge coefficient has an increasing trend. By comparing the discharge coefficient in different situations, the discharge coefficient in the upstream tangential position is higher than the sill in the below position of the sluice gate. The reason is related to the position of the sill. For the downward tangent model compared to the sill below the gate, the discharge coefficient is higher, and compared to the upward tangent model is lower. In the upstream tangential model, the amount of water depth upstream of the gate is lower than the below and downward model, and the highest amount is related to the sill state below the gate. At the same opening in the without sill and suppressed sill state, the maximum discharge coefficient is related to the sill state. In the stage-discharge diagram at constant discharge, the water head upstream of the sluice gate is lower in all suppressed sill positions than the no-sill state. In this study, equations were presented for predicting discharge coefficient in with and without sill state.

The results showed that in no-sill state and in different gate openings, the discharge coefficient is inversely related to the gate opening. In the present study, the general equation of discharge calculation was developed for the non-suppressed sill and the calculations were performed based on the new relation presented for the case with the non-suppressed sill. This equation can be used for symmetric and asymmetric sills. Comparison of the results obtained for the discharge coefficient, with sill, and without sill condition indicates the better performance of the existence of a sill in all positions in terms of increasing the discharge coefficient. In addition, the comparison of the results of discharge coefficients between the suppressed sill and no-sill state in the opening of 1 and 2 cm indicates an increase of the discharge coefficient in the suppressed sill state. In this condition, the discharge coefficient of the gate opening of 1 cm is higher than 2 cm. However, the discharge coefficient is higher in both opening modes than in the without sill mode.

Iran is located in an arid and semi-arid climate with an average rainfall of about 239.3 mm during five years ago. There are many challenges for decision-makers in terms of supplying water for agriculture, industry, and drinking. On the other hand, lack of comprehensive decision-makers, along with lack of awareness of beneficiaries of the consequences of excessive use of groundwater resources, has led to land subsidence in most plains of the country. This issue, due to the nature of land cognition and its relation to the use of groundwater, has been considered by researchers in the fields of water resources management and geology. Land subsidence of Iran has been studied worldwide and the effects of groundwater abstraction have been determined at a high level compared to other factors. Hamedan province in the western part of Iran is not far from overuse of water and the effects of land subsidence, due to the extensive agricultural lands and agricultural hubs. In this regard, studying Kaboudrahang aquifer subsidence with its sinkholes (18 massive sinkholes) was selected as the study site in the northwest of Hamadan province. The hydrograph of the plain aquifer unit shows a profound drop in the groundwater level of the aquifer (40 meters) between the years 1988 and 2018.

Regarding plain subsidence, some researches have been done. Accordingly, the radar interference technique in ENVI software was used to determine the amount of land subsidence and finally its output expressed in GIS software. To use this method, 11 Sentinel satellite images from 2014 to 2019 were selected and groundwater changes in 49 observation wells were studied. To investigate land subsidence and groundwater changes, the relation between land subsidence rate and groundwater level drop was examined through a regression analysis, as well as several observation wells that have a reduction in the date of the last satellite image relative to the water level. A regression analysis was selected between the water level drop and land subsidence rate and between the water level drop and the cumulative land subsidence obtained by radar interferometry during the period. To investigate in more detail, the effect of groundwater abstraction in each observation well and the relationship between land subsidence and its changes over time have also been investigated. On the other hand, land subsidence is delayed according to some research on groundwater exploitation, which varies due to the different hydraulic conductivity of the aquifer along with the different geological structures of the plain. Lag regression was used as a simple tool to determine the lag time between groundwater exploitation and land subsidence.

The study results showed that during the years 2014 to 2019, the land subsidence of the plain was 124.7 mm and an average rate was 13 mm every six months. Positive and negative values were observed in the land subsidence rate map in which positive values indicate upward radar visibility and negative values are related to radar visibility or subsidence. In general, across the plain, there is no equal correlation between subsidence rate and groundwater level decline. Its main reason can be found in the difference of geological structures and diverse soil texture throughout the plain, which has led to different responses to groundwater exploitation. Wells that had a drop in water level between the first and last satellite image show a decreasing trend of land subsidence rate and cumulative land subsidence. This indicates a decrease in the power of land subsidence in the utilization of water over time. The reason is that groundwater passed through subsidence-sensitive layers, after which the effect on land subsidence is reduced. The lag time of subsidence and operation of groundwater was determined as an average of 1.5 years.

Based on the analysis of this research, more significant impact of land subsidence on agricultural lands can be identified due to the use of groundwater. On the other hand, there is need for proposals and solutions to reduce the rate of land subsidence, and so it is recommended to change the cultivation pattern, to control surface water with artificial recharge, and to create deep plowing in agricultural areas to increase permeability.

Most of the soils in Iran are affected by over-accumulation of calcium carbonate (CaCO3). It is estimated that more than 87 percent of the agricultural soils have more than 5% equivalent calcium carbonate. In these soils, the addition of elemental sulfur is known to be desirable for the elimination of nutritional disorders which has been caused by high pH. Sulfur could reduce soil pH and increase the bioavailability of elements like Fe, P and, etc. Such management also may change the environmental conditions around microbes in the soil and alter their activities in soil media. Soil quality is strongly depending on soil pH so, it will be affected by sulfur application in the soil. However, the impact of this management on soil biological activities has not received adequate attention. Therefore, the aim of this study was to investigate the effect of sulfur as well as its integrated application with animal manure and Sulfo Baravar-1 containing sulfur oxidizing bacteria on the biological parameters of a calcareous soil.

An unfertile soil sample was picked up from non-cultivated condition having 16% lime content. A factorial experiment as randomized complete blocks design was conducted with the elemental sulfur application (zero (S0), 1 % (S1), and 2 % (S2)), organic manure from cow waste (application of 1% cow manure and non-application), inoculation of Sulfo Baravar-1 Biofertilizer (inoculation and non-inoculation). The effects of treatments on soil pH and soil biological properties such as soil organic matter (SOM), soil respiration, microbial biomass carbon (MBC), and substrate induced respiration (SIR) were investigated for 60 days after treatments. Soil microbial metabolic quotient (qCO2), soil microbial quotient (qmic) and, the ratio of qCO2/SIR were calculated as well.

The results showed that, addition of sulfur, sulfur plus organic manure and, Sulfo Baravar-1 inoculation decreased soil pH. Most pH reduction was occurred at 2% sulfur application. In response to soil pH variation, soil respiration increased with different patterns between the treatments. Although, the sulfur application could increase soil basal respiration but, the highest value was seen in organic manure plus 2% sulfur treatment. Despite increasing of CO2 emission from the soil due to respiration, the meaningful variation in SOM was not seen in sulfur treatments. Organic manure application increased SOM content by 0.15 %. MBC increased by 52% and 72 % respectively in 1% and 2% sulfur application in respect to control. Organic manure application along with sulfur had a positive effect on MBC, but this trait was not affected by Sulfo Baravar-1 inoculation. The ratio of qCO2/SIR was reduced by sulfur application up to 98% in S1 and 400% in S2 treatments, respectively. The sulfur application with Sulfo Baravar-1 inoculation and without its inoculation decreased qmic by 47% and 80%, respectively. While, sulfur application along with manure shifted this trend vice versa and qmic increased 34% in respect to control (S0). Sulfur application also increased substrate induced respiration at S1 and S2 at a rate of 90% and 94%, respectively, and increased metabolic coefficient (qCO2) in S1 and S2 treatments 2.7 and 370%, respectively in respect to control. qmic and SIR were not affected by organic manure application and Sulfo Baravar-1 inoculation to the soil. Based on the results, there was a linear correlation between soil microbial biomass carbon, soil basal respiration (R2= 0.98) and qCO2 (R2=0.82). Substrate induced respiration had a relatively weaker correlation with soil microbial biomass carbon (R2=0.27).

All the treatments decreased soil pH compared to controls but, more decline of soil pH was observed in 2% sulfur applied treatments especially in organic manure plus sulfur application. SOM quantity and quality are important factors of soil quality as well as its sustainability. Sulfur application plus organic manure had a positive effect on SOM content, and qmic as an index of SOM quality. Therefore, the application of animal manure along with sulfur will increase soil quality as well as improves the soil pH. Due to the destructive effects of the sole application of elemental sulfur on soil biological traits, the application of sulfur is recommended with organic manure for the soils rich in calcium carbonate.

Intensity-duration-frequency (IDF) curve is one of the most common tools used in water resources management (Bernard 1932). In this regard, obtaining IDF curves plays an important role in designing of hydraulic structures such as dams and water transfer canals. Intensity, duration and frequency of precipitation are changed according to the change in the hydrological cycle and the increase of greenhouse gases. The optimal designs of surface runoff systems extremely rely on IDF rainfall curves (Liew, et al. 2014). Since rainfall characteristics are often used for designing hydraulic structures, it is necessary to review and update rainfall characteristics such as the IDF curve for the future climate scenarios (De Paola, et al. 2014). Climate change affects the intensity and frequency of rainfall as well as runoff in future periods. According to the studies conducted in the western reversible flood basin, the amount of runoff and maximum flows and the probability of flooding will increase significantly in the future time horizon, (Binesh, et al. 2018). As well, it is necessary to define the flood peak thresholds in order to determine the discharge values for different return periods, for which it is necessary to determine the maximum precipitation values with a certain intensity and continuity for future periods (Van, et al. 2020). According to the researches, it seems that the effect of climate change on marginal currents in urban basins has been less considered. Therefore, in the present study, using the SDSM model outputs according to the fifth report, intensity- duration- frequency (IDF) curves under the influence of climate change scenarios were extracted for Shemiran, Geophysic and Mehrabad synoptic stations located in Tehran province with different return periods in order to better evaluate the role of climate change on the intensity of rainfall and floods in the basin and to consider the necessary measures in accordance with the conditions ahead.

The data of historical storms of meteorological stations is used to obtain the intensity-duration-frequency curves. In the present study, IDF curves of Shemiran, Geophysic and Mehrabad synoptic stations located in Tehran province influenced by climate change of the historical period (1991-2015) with 2, 5, 10, 25, 50 and 100 year return periods were extracted. SDSM software version 5.3 has been used for downscaling. Based on the following downscaling, precipitation forecasting was performed under three scenarios: RCP2.6, RCP4.5 and RCP8.5 for 5 periods of 15 years and a period of 10 years from 2016 to 2100. The SCS method has been used to calculate the concentration time in this study. Three criteria of correlation (r), Nash Sutcliffe coefficient (NSE) and Bias were used to evaluate the efficiency of SDSM model. The proposed method of the US Soil Conservation Organization is based on the proposal of the World Meteorological Organization (WMO) about the temporal distribution pattern of storms. The amount and intensity of precipitation in each return period is calculated by means of this temporal distribution pattern. 6-hour precipitation was obtained under RCP scenarios for different return periods using the hero relationship.

In this study, forecasts for the next 50 years indicate that the rainfall will decrease by 16.55% and 14.36% at Shemiran station according to the RCP2.6 and RCP8.5 scenarios. Compared to the observational state; however, precipitation will increase by 45.24% based on the RCP4.5 scenarios. At the Geophysic station, the annual rainfall will decrease by 25.12 and 16.8 percent based on the scenarios of RCP2.6 and RCP8.5, but it will increase by 20.61 percent based on the RCP45. The precipitation at Mehrabad station will decrease in all scenarios. The precipitation at Mehrabad station will decrease by 11.038, 10.6 and 5.75, respectively under the scenarios of RCP2.6, RCP4.5 and RCP8.5.

In the present study, it is found that the rainfall intensity by comparing the obtained IDF curves in Shemiran, Geophysic and Mehrabad synoptic stations under RCP2.6 scenario has dramatically increased by 45.66, 54.49 and 31.74 percent in comparison to the base period for the return period of 50 years. RCP4.5 scenario contains 40.89, 61.5 and 43.9% and RCP8.5 scenario contains 65.77, 66.12 and 48.6 percent. Finally, using the extracted IDF curves for Shemiran, Geophysic and Mehrabad synoptic stations, the maximum flow influenced by climate change was compared with the base flow. The results show that the maximum discharge is increasing. According to the results, the maximum flow rate based on the rainfall intensity obtained at Shemiran station increased by at least 40.89% and at most 65.77% under the influence of RCP4.5 and RCP8.5 scenarios for the return period of 50 years compared to the maximum of base flow. According to the intensity of precipitation calculated at the geophysic station, the maximum flood discharge increased by about 54% with the RCP2.6 scenario and about 66% with the RCP8.5 scenario compared to the base period. Finally, by comparing the maximum discharge under the influence of climatic scenarios and the maximum of base flow (based on calculated by rainfall intensity) at Mehrabad station, it was determined that the minimum increase of the maximum of base flow is related to RCP2.6 scenario was 31.74% and the maximum increase was related to RCP8.5 scenario which is 48.61%

Biofertilizers play major role in sustainable agriculture. For provide them, different carriers are used to increase the longevity and survival of the bacteria. Biofertilizers are being used in two general forms; solid or liquid. For making biofertilizers, various types of material are used to inoculate seed or soil. A suitable material for carrying microorganisms should have certain characteristics such as high water holding capacity, chemical and physical uniformity, easy to sterilize by autoclaving or gamma-irradiation, absence of toxic compounds for microbial strains, and environmental safety. At the same time, these materials should have a near-neutral or easily adjustable pH and be locally abundant at reasonable cost. Liquid or solid biofertilizers have their own advantages or disadvantages. The aim of this study was to investigate the survival of Enterobacter cloacae S16-3 bacterium on different liquid carriers during one year.

The liquid carrier consisted of 9 treatments containing glycerol, polyethylene glycol (PEG), trehalose, carboxymethyl cellulose (CMC), arabic gum, polyvinyl pyrrolidone (PVP), glucose and starch with different amounts and in different combinations. In this study, bacterial inoculants prepared with the same initial population (109 CFU mL-1) after storage at room temperature were compared for the survival of the bacterium. The bacterial population was counted at 0, 15, 30, 60, 90, 120, 180, 270 and 365 days. For counting the bacteria in microbial carriers, after dilution series preparation, bacterial suspension was used in strip culture in a plate. In this research, the effects of prepared inoculants on germination and growth of wheat seedlings in sterile conditions in a plate and pot culture at the end of the fourth month were investigated. In pot culture, characteristics such as shoot and root length, the wet and dry weight of shoot and root, total wet and dry weight of shoot and root were measured.

The bacterial counting results showed that among the tested carriers, the most population was counted after one year in formulation F5 (arabic gum, starch and PEG) (107 CFU mL-1) and the lowest population was counted in formulation F7 (glycerol, trehalose, glucose, arabic gum, and PEG), so that after 6 months no alive cells of bacteria were counted. Also, the results of germination test and growth of wheat seedlings cultivating in a plate showed that the materials used in microbial carriers did not have any inhibitory effect on germination of the seeds, and even, in some cases, they could encourage their germination and growth. So that ten seeds in each inoculum started to germination simultaneously. In pot culture, F9 formulations (glycerol, glucose, arabic gum and PEG), and F4 (trehalose, arabic gum, and PEG) in terms of root fresh weight and total fresh weight had better means. The root fresh weight of the formulations were 1020 and 740 mg and the total fresh weight of 1800 and 1390 mg, respectively. The comparison of these carriers with control (without bacteria and carrier) and suspension of bacteria (non-carrier inoculation) showed that these carriers could be more effective in all measured characteristics.

Currently, the application of different materials in bacterial liquid formulation is considered to be of high importance as an innovative technological strategy to maintain the metabolic stability of microorganisms. Finally, according to the results of this experiment and the convenience and availability of the carriers, the F5 and F9 formulations can be suggested for further studies.