Water and Soil

Abstract Introduction Soil compaction is a significant component that has a detrimental impact on soil structure, inhibits plant development, lowers water penetration rate, diminishes crop production, and raises machine (tractor, cultivator…) usage costs. In general, compaction is the result of applied pressure that results in a rise in bulk density or decreased in soil porosity. One of the most used indices for the investigation and evaluation of soil compaction is based on penetration resistance (PR) of the soil. However, identifying soil compaction by the records of soil penetrometer equipment in the field is time-consuming, expensive, and may produce unreliable results due to instrumental errors; Thus, it is useful to apply different intelligent models to predict PR through easily accessible and low-cost soil parameters. The aim of this study was to compare the performance of three intelligent models -neuro-fuzzy (NF), gene expression programming (GEP), and random forest (RF)—in estimating PR from readily available soil variables.

Materials and methods Disturbed and undisturbed soil samples (n= 105) were collected from 0-10 cm depth of agricultural lands in Ardabil plain, Iran. The values of sand, silt, clay, CaCO3, bulk (BD) and particle (PD) density, organic carbon (OC), field water content (FWC) and saturated water were measured at the soil samples in the laboratory according to the standard methods. Mean geometric diameter (dg) and geometric standard deviation (σg) of soil particles were calculated by sand, silt and clay percentages. Total porosity (n) was computed using BD and PD data. The penetration resistance (PR) of the soil was obtained in the field using cone penetrometer (analog model) at 5 replicates. Data randomly were divided in two series as 78 data for training and 27 data for testing of models. Fifteen different combinations of readily available soil variables were selected as model inputs to estimate PR using neuro-fuzzy (NF), gene expression programming (GEP), and random forest (RF) models. The triangular, sigmoid, trapezoid, Gaussian and bell shape membership functions in the input layer and constant membership function in the output layer by trial and error method were applied in the neuro-fuzzy (NF) modeling using MATLAB program. A set of optimal parameters were chosen before developing a best GEP model in the Gene Xpro Tools 4.0 software. The number of chromosomes and genes, head size and linking function were selected by the trial and error method, and they are 30, 3, 8, and +, respectively. The rates of genetic operators were chosen according to literature studies. Weka software was used planning random forest (RF) models. The accuracy of NF, GEP and RF models in estimating PR were evaluated by coefficient of determination (R2), normalized root mean square error (NRMSE), mean error (ME) and Nash-Sutcliffe coefficient (NS) statistics.

Results and discussion The values of sand (26.26 to 87.43 %), silt (5.99 to 67.18 %), clay (3.99 to 17.34 %), OC (0.30 to 2.41 %), FWC (4.56 to 33.18 mass percent), BD (1.02 to 1.63 g cm-3) and PR (1.10 to 6.60 MPa) indicated good variations in the soils of studied area. There were found significant correlations between PR with FWC (r= - 0.57**), sand (r= - 0.21*), OC (r= - 0.47**) and BD (r= 0.66**). More former researchers also reported that there is a negative and significant correlation between PR with FWC and a positive and significant correlation between PR with BD. The results of NF, GEP and RF models showed that the most suitable variables to predict PR were field water content (FWC), sand, bulk density (BD), total porosity and mean geometric diameter (dg) of soil particles. Values of coefficient of determination (R2), normalized root mean square error (NRMSE), mean error (ME), and Nash-Sutcliffe coefficient (NS) were calculated for the best models based on the test data as follows: 0.50, 0.19, 0.03 MPa, 0.51 for NF; 0.51, 0.20, 0.13 MPa, 0.48 for GEP; and 0.58, 0.20, 0.31 MPa, 0.50 for RF.
Conclusion The results showed that according to the lowest values of normalized root mean square error (NRMSE) and the highest values of Nash-Sutcliffe coefficient (NS), the accuracy of neuro-fuzzy (NF) model to estimate soil PR was more than gene expression programming (GEP) and random forest (RF) models in this study; The input variables of the best NF model in estimating soil penetration resistance (PR) were field water content (FWC), sand and bulk density (BD).

Abstract Introduction
Water conveyance tunnels are critical infrastructures for sustainable water supply, particularly in arid and semi-arid regions. However, tunnel excavation can significantly alter groundwater systems, leading to hazards such as sudden groundwater inflow, reduction in aquifer storage, and deterioration of water quantity and quality (Zheng et al., 2021; Li et al., 2024). In fractured and karstic environments, these impacts may propagate over large distances, potentially modifying regional hydrogeological regimes (Chen, 2021; Sadique et al., 2025).
To address these challenges, various predictive approaches have been developed, including numerical modeling, parametric methods, hybrid techniques, and empirical models. Although numerical models provide detailed insights, they require extensive datasets and complex calibration, which limits their applicability in heterogeneous geological settings (Vincenzi et al., 2022). Consequently, parametric and empirical methods such as the Drainage Hazard Index (DHI) and Tunnel Impact Score (TIS) have gained increasing attention due to their flexibility, simplicity, and suitability for preliminary assessments and real-time decision-making (Dematteis et al., 2001; Hassanpour et al., 2021; Abedian & Mojiri, 2023).
The Hezarmasjed water conveyance tunnel, located in northeastern Iran within the Kopet-Dagh tectonic zone, traverses a highly fractured carbonate system hosting numerous springs. Given the dependence of local communities on these springs, assessing the potential impacts of tunnel excavation is essential. This study aims to identify the main controlling factors governing spring discharge variations and to evaluate the vulnerability of springs using both DHI and TIS approaches.

Materials and Methods
The study area is situated in a structurally complex mountainous region characterized by active tectonics, heterogeneous lithology, and significant hydrogeological sensitivity. The tunnel, approximately 8.8 km in length, intersects several geological formations, including carbonate units (Mozduran and Tirgan) acting as primary aquifers, and shale-dominated formations with low permeability. Groundwater flow is predominantly controlled by fracture networks and karstification processes, resulting in rapid hydrological responses to precipitation events.
A total of 45 springs were investigated at varying distances from the tunnel axis. Field data included hydrogeological observations, Lugeon permeability tests, and structural analyses. Permeability values generally ranged from 10⁻⁷ to 2.5×10⁻⁶ m/s, indicating low to moderate hydraulic conductivity, with higher values in fractured and karstified zones.
Two complementary methods were employed for impact assessment. The DHI method (Dematteis et al., 2001) is a semi-quantitative parametric approach based on seven key parameters, including fracture frequency, rock mass permeability, overburden thickness, plastic zone radius, fault–spring interaction, spring type, and distance from the tunnel. These parameters were normalized and combined to calculate a continuous index representing the risk of spring discharge reduction.
The TIS method (Hassanpour et al., 2021) is an empirical approach that evaluates spring vulnerability based on four main factors: tunnel water inflow (40% weight), hydraulic connectivity (40%), distance from the tunnel (15%), and aquifer recharge capacity (5%). The method provides a classification of impact severity, ranging from negligible to significant discharge reduction.

Results and Discussion
The DHI results indicate that spring vulnerability is primarily controlled by structural and hydrogeological parameters, particularly fracture density and permeability. Calculated DHI values range from 0.1 to 1.5, demonstrating a wide spectrum of potential impacts. Approximately 11% of springs are classified as highly to critically affected (DHI ≥ 0.6), while the majority (about 89%) are expected to experience minor to moderate discharge reductions. Springs with high DHI values are typically located in highly fractured carbonate formations with strong hydraulic connectivity, where tunnel excavation acts as a drainage boundary, intercepting groundwater flow paths (Vincenzi et al., 2022; Saberinasr & Dashti Barmaki, 2023).
In contrast, springs located in low-permeability formations or at greater distances from the tunnel exhibit minimal sensitivity, with DHI values below 0.2. More than 70% of springs fall within an intermediate range, indicating moderate but persistent reductions due to partial hydraulic connectivity.
The TIS results highlight the importance of dynamic hydrogeological parameters, particularly tunnel water inflow and hydraulic connectivity. TIS values range from 1.6 to 6.9, reflecting significant variability in system response. Approximately 44% of springs are classified as unaffected, 44% experience moderate discharge reduction, and around 12% are subject to significant decline.
High-risk springs, such as Sirzar and Bamchenar, exhibit strong hydraulic connectivity and are located within sensitive recharge zones. Notably, the results indicate that hydraulic connectivity can dominate system behavior even at distances exceeding 1000 m, confirming previous findings that connectivity is more influential than geometric proximity (Hassanpour et al., 2021).
Conversely, springs located in areas with higher recharge capacity and weaker hydraulic connectivity show minimal impact, even when tunnel inflow is relatively high. This behavior reflects the buffering capacity of aquifer systems, which can partially compensate for tunnel-induced drainage.
A comparative analysis of the two methods demonstrates that the DHI approach emphasizes intrinsic geological and structural conditions, providing a continuous representation of vulnerability, whereas the TIS method focuses on functional aquifer responses and offers a more practical classification of impact severity. The consistency between both methods in identifying high-risk springs supports the reliability of the integrated approach.

Conclusion
This study demonstrates that tunnel excavation can significantly affect groundwater systems, particularly in fractured and karstic aquifers. The integrated application of DHI and TIS methods provides a comprehensive framework for assessing these impacts.
The DHI method is effective for identifying intrinsic vulnerability and worst-case scenarios, highlighting the role of geological structures, permeability, and fracture density. Approximately 11% of springs are at high to critical risk, while most are expected to experience moderate impacts.
In contrast, the TIS method offers a more operational perspective by incorporating dynamic hydrogeological parameters, classifying springs into significant, moderate, and negligible impact categories. The results emphasize the dominant role of hydraulic connectivity and aquifer recharge capacity in controlling system response.
Overall, the combined use of parametric and empirical approaches enhances the reliability of impact assessments and provides a robust basis for groundwater management in tunnel projects. This integrated methodology is particularly suitable for complex hydrogeological environments where data limitations restrict the application of numerical models.

Abstract Introduction
Tillage management is one of the main factors affecting soil quality and the sustainability of agricultural systems. Intensive conventional tillage can weaken soil structure, accelerate organic matter decomposition, and alter microbial activity due to continuous mechanical disturbance of the soil. In contrast, conservation tillage systems such as reduced tillage and no‑tillage minimize soil disturbance and often retain crop residues on the soil surface, which can improve soil aggregation, enhance soil organic carbon storage, and increase nutrient retention. These systems also help reduce soil erosion, improve water infiltration, and create more favorable conditions for soil microorganisms. In semi‑arid regions, where soil moisture is limited and soil degradation can occur rapidly, maintaining soil structure and fertility is particularly important for crop production. Durum wheat is an important cereal crop in many semi‑arid areas, and its productivity is closely related to soil health and nutrient availability. Therefore, understanding how different tillage systems influence soil properties is essential for developing sustainable management strategies. This study was conducted to evaluate the effects of different tillage systems and crop presence on selected physical, chemical, and biological properties of soil.
Materials and Methods
The experiment was conducted as a split-split-plot arrangement within a randomized complete block design (RCBD) with three replications. The treatments consisted of three tillage systems, including conventional tillage (CT), reduced tillage (RT), and no-tillage (NT), assigned to the main plots. The subsoiling treatments, including subsoiling and no-subsoiling, were allocated to the subplots, and two crop treatments, including control (uncultivated soil) and durum wheat (Triticum durum), were assigned to the sub-subplots. Soil samples were collected after the crop growing period from the experimental plots and prepared for laboratory analysis. A set of soil quality indicators representing physical, chemical, and biological aspects of soil functioning was measured. Physical and chemical assessments included pH, electrical conductivity (EC), water dispersible clay (WDC), and mean weight diameter (MWD) of aggregates, which were used to evaluate salinity condition and aggregate stability. Chemical analyses included soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (P), and available potassium (K) as the main indicators of soil fertility and nutrient status. Biological properties were determined through basal soil respiration (BR) and substrate induced respiration (SIR), in order to estimate microbial activity and the potential metabolic response of soil microorganisms to an added substrate. In addition, microbial biomass carbon was considered in the interpretation of biological responses where relevant. The collected data were statistically analyzed using analysis of variance (ANOVA) to test the significance of the main effects of tillage and crop treatment as well as their interaction effects on soil properties. Mean comparisons were performed using appropriate post hoc tests at the selected probability level.
Results and Discussion
The results showed that tillage management significantly influenced the measured soil properties. Conventional tillage generally resulted in higher EC and water dispersible clay, indicating weaker structural stability, whereas no tillage improved aggregation and produced the highest mean weight diameter of soil aggregates. These results confirm that reduced soil disturbance promotes aggregate formation and protects soil structure. Soil organic matter and soil organic carbon increased as tillage intensity decreased, with the highest values observed under no tillage. This trend indicates that conservation systems reduce oxidation of organic materials and favor carbon accumulation within stable aggregates. Nutrient availability also improved under conservation practices, particularly in the no tillage treatment, where nitrogen, phosphorus, and potassium values were generally higher than in conventional tillage. Crop treatment had a positive effect on several soil properties. Soils under durum wheat showed higher soil organic matter, soil organic carbon, and nutrient concentrations than uncultivated control soils, probably because of root residues, rhizosphere activity, and enhanced microbial interactions. Biological indicators also responded significantly to management practices. Basal respiration was greater under conventional tillage, suggesting more rapid decomposition of soil organic matter under intensive disturbance. In contrast, lower respiration values under no tillage reflected greater stabilization of organic carbon. Substrate induced respiration was significantly affected by tillage, crop treatment, and their interaction, indicating that microbial activity was highly sensitive to both soil disturbance and plant presence.
Conclusions
The findings demonstrate that tillage management has an important role in controlling soil quality in durum wheat systems. Conservation practices, especially no tillage, improved soil structure, increased soil organic carbon and organic matter, and enhanced nutrient availability compared with conventional tillage. Durum wheat cultivation also contributed positively to soil improvement through rhizosphere effects and organic inputs. Overall, the combination of no tillage and durum wheat cultivation appears to be a suitable management strategy for improving soil quality and supporting sustainable production in semi arid conditions.

Abstract Introduction: Degradation of water quality has emerged as one of the most critical challenges facing national water resources. Surging water demand has led to the over-exploitation of groundwater and a continuous decline in aquifer levels, subsequently triggering environmental degradation and a deteriorating trend in groundwater quality. Consequently, analyzing temporal trends and spatial variations of groundwater quality is vital for sustainable water resource management. This study aims to investigate the temporal trends of groundwater quality parameters using the Mann-Kendall test and Sen’s Slope Estimator, while analyzing spatial variations through the Groundwater Quality Index (GQI) in the Bahabad aquifer.
Materials and Methods: In this study, a total of 16 observation wells were initially considered for groundwater quality assessment. Among them, 9 wells with complete and reliable datasets were selected for detailed analysis. The required hydrochemical data were obtained from the Yazd Regional Water Authority and included major groundwater quality parameters: calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺), chloride (Cl⁻), sulfate (SO₄²⁻), and total dissolved solids (TDS). A uniform temporal period from 2002 to 2023 was considered for all selected wells to ensure consistency in trend analysis.
To evaluate temporal variations in groundwater quality, non-parametric statistical methods, including the Mann–Kendall test and Sen’s slope estimator, were employed. These methods are widely used in hydrochemical studies due to their robustness against non-normal data distributions and their ability to detect both the direction and magnitude of trends over time.
Spatial variations in groundwater quality parameters were analyzed using a range of interpolation techniques, including both deterministic and geostatistical approaches. The applied methods consisted of Inverse Distance Weighting (IDW), Radial Basis Functions (RBF), Local Polynomial Interpolation (LPI), Global Polynomial Interpolation (GPI), and Kriging. All spatial analyses were performed in a GIS environment. The optimal interpolation method for each parameter was selected based on statistical performance indicators, primarily the lowest Root Mean Square Error (RMSE) and the highest coefficient of determination (R²).
Prior to spatial modeling, the normality of the dataset was evaluated using the Kolmogorov–Smirnov and Shapiro–Wilk tests, which are commonly applied to assess data distribution characteristics. The results of these tests were used to determine whether data transformation was required before applying interpolation and statistical analyses.
Finally, the Groundwater Quality Index (GQI) was calculated to provide an integrated assessment of groundwater quality conditions. By aggregating multiple hydrochemical parameters into a single index, GQI enables a comprehensive evaluation of groundwater quality and facilitates spatial comparison across the aquifer. This index was used as a key tool for interpreting overall water quality status and supporting groundwater management decisions.
Results and Discussion: The results indicate that while the groundwater quality of the Bahabad aquifer remained within the “Acceptable” category during the study period, a slight but statistically significant downward tendency in quality was observed. Spatial distribution analysis revealed that salinity patterns and ionic concentrations are influenced more by anthropogenic pressures such as over-pumping, water table drawdown, and inter-basin water transfer than by natural geological factors.
Temporal analysis highlighted significant spatial heterogeneity; for instance, Mg²⁺ exhibited a significant increasing trend across all stations (Sen’s slope ranging from 0.05 to 0.23), whereas Na⁺ and SO₄²⁻ showed decreasing or insignificant trends in certain wells. TDS displayed variable behavior, showing generally stable or slightly decreasing trends, while a sharp increase was observed at one specific station.
Furthermore, a comparison of interpolation techniques showed that under conditions of limited sampling density and weak spatial correlation, deterministic methods often yielded higher predictive accuracy than geostatistical models.
Conclusion: Despite only minor overall fluctuations in the GQI (ranging approximately between −0.5% and +0.1%), the index maps did not fully capture the intensity of localized quality degradation in critical parameters such as TDS, Na⁺, and SO₄²⁻. This indicates that composite indices like GQI may partially neutralize opposing trends among individual parameters, thereby providing a more generalized representation of groundwater quality conditions.
Trend analysis of individual parameters revealed considerable spatial heterogeneity across the aquifer. Magnesium and chloride exhibited consistent increasing trends in most monitoring wells, indicating progressive salinization, whereas sodium and sulfate showed mixed or insignificant trends in several locations. Total dissolved solids demonstrated spatially variable behavior, with localized sharp increases despite generally stable or declining trends elsewhere. This variability reflects the complex interaction between local hydrogeological conditions and human-induced pressures and confirms that groundwater quality evolution cannot be adequately described using a single parameter or uniform trend assumption.
The comparison of interpolation techniques further highlighted an important methodological implication: under conditions of limited sampling density and weak spatial autocorrelation, deterministic methods can provide more reliable estimates than geostatistical approaches. This emphasizes the need to adapt modeling strategies to data availability and hydrogeological settings, particularly in arid and semi-arid regions where monitoring networks are often sparse.
Although the Groundwater Quality Index proved effective in providing an overall assessment of groundwater status, it was less sensitive to localized deterioration in key parameters such as TDS, sodium, and sulfate. This confirms that composite indices, while useful for communication and management purposes, may mask emerging local-scale risks if used in isolation. Therefore, they should be applied alongside parameter-specific analyses rather than as standalone decision-making tools.
Overall, the findings highlight the urgent need for improved groundwater management in the Bahabad aquifer. Controlling excessive abstraction, regulating industrial withdrawals, and strengthening long-term monitoring programs are essential to prevent further degradation. Integrating spatial analysis with trend-based assessments can provide a more reliable framework for sustainable groundwater management, particularly in arid regions experiencing increasing water stress.

Abstract Introduction
The heavy reliance on chemical N-P-K fertilizers in intensive vegetable farming has raised significant environmental and health concerns. Nitrate accumulation in leafy greens, especially spinach, is a major food safety challenge. Nitrate is directly linked to nitrogen metabolism and accumulates in plant tissue when its uptake exceeds the plant's capacity to use it for growth and protein synthesis. Plant growth-promoting bacteria (PGPB) offer a sustainable alternative by enhancing nutrient bioavailability through mechanisms such as phosphate solubilization, nitrogen fixation, and siderophore production. Growth-promoting bacteria prevent nitrate accumulation in leaves by improving nitrogen uptake and transport. While the efficacy of PGPB is well-documented in cereal crops, their potential to mitigate the negative effects of reduced fertilization in high-demand vegetables like spinach remains under-explored.
Materials and Methods
This study aimed to evaluate the efficiency of PGPB in improving spinach characteristics under greenhouse conditions using a factorial experiment based on a completely randomized design. The treatments consisted of two levels of N-P-K fertilizer (100% of recommended rate and 70% of the recommended rate) and four levels of microbial inoculation (no bacteria, Pseudomonas putida, Phytobacter diazotrophicus, and a mix of both). The experiment was conducted in 3 kg pots. Six seeds were sown 1 cm below the soil surface and one milliliter of each strain was inoculated under each seed. The soil moisture of the pots was maintained at approximately 75% of field capacity moisture by weight during the experiment. After two weeks, the plants were thinned to three plants. The plants were harvested 50 days after planting. Parameters including leaf nitrogen (N), phosphorus (P), potassium (K), iron (Fe), chlorophyll content, nitrate concentration, and nitrate reductase enzyme activity were measured.

Results
The results showed that the interaction effect of fertilizer level and bacterial inoculation was significant for all measured traits. Microbial inoculation, particularly the mix of bacteria, effectively compensated for the yield loss caused by the 30% reduction in chemical fertilizer. The highest leaf fresh weight was obtained in both the 100% and 70% recommended NPK fertilizer treatments when plants were inoculated with the combined bacterial consortium, representing 1.7- and 2.2-fold increases, respectively, compared with the corresponding non-inoculated treatments. Application of 100% of the recommended NPK fertilizer in combination with the mixed bacterial inoculum increased leaf nitrogen (62%), phosphorus (23%), potassium (51%), and iron (32%) contents compared with the corresponding non-inoculated treatment. The second-highest contents of these nutrients were observed in the treatment receiving 70% of the recommended fertilizer rate together with the mixed bacterial inoculum. Total chlorophyll content declined with reduced fertilizer application; however, bacterial inoculation compensated for this reduction, such that no significant difference was observed between the inoculated treatments and the treatment receiving 100% of the recommended fertilizer rate. The highest total chlorophyll content was measured in the treatment receiving 100% of the recommended fertilizer rate together with the mixed bacterial inoculum,
which was 34% higher than the corresponding non-inoculated treatment. The highest leaf nitrate content (6123 mg kg⁻¹) was recorded in the treatment receiving 100% of the recommended fertilizer rate without bacterial inoculation. The lowest leaf nitrate content was measured in the treatment receiving 70% of the recommended fertilizer rate combined with the mixed bacterial inoculum, representing a 25% reduction compared with the corresponding non-inoculated treatment. The highest nitrate reductase activity was measured in the treatment receiving 70% of the recommended fertilizer rate together with the mixed bacterial inoculum, showing a 47% increase compared with the corresponding non-inoculated treatment. There was a negative correlation between nitrate content in the leaf and nitrate reductase activity. The results indicated that chlorophyll content was positively correlated with the contents of nitrogen, phosphorus, potassium, and iron, as well as with nitrate reductase activity. Plant fresh weight was also positively correlated with chlorophyll content, the contents of nitrogen, phosphorus, potassium, and iron, and the activity of nitrate reductase.


Conclusion
Overall, these findings suggest that the combined application of Pseudomonas putida and Phytobacter diazotrophicus with 70% of the recommended NPK fertilizer rate may represent a promising strategy to reduce chemical fertilizer use by 30% without substantial yield loss, while enhancing the nutritional quality of spinach. Nevertheless, further validation under field conditions and diverse environmental settings is required before this approach can be recommended for widespread agricultural use.

Abstract : Earth-fill dams with clay cores are pivotal hydraulic structures for potable water supply, agriculture, and flood management; however, over 35% of their historical failures are attributed to seepage and internal erosion. This study focuses on the Nahand Earth-fill Dam (East Azerbaijan Province) and numerically investigates the impact of a 10% increase in the geometric dimensions of the vertical-horizontal chimney drain specifically increasing length from 15 m to 16.5 m and thickness from 1.5 m to 1.65 m using the Finite Element Method (FEM) in GeoStudio 2024. The 10% increment step was selected based on initial sensitivity analysis and reference benchmarks. The numerical model was developed using a mesh of 12,800 quadratic elements, incorporating realistic boundary conditions (upstream hydraulic head of 35 m and downstream head of 5 m). Comprehensive validation was performed using 18 years of instrumentation data from 22 piezometers and 6 observation wells, achieving a coefficient of determination (R2) of 0.982 and a Root Mean Square Error (RMSE) of 0.68 m. The results indicated that this geometric optimization led to: a 22.3% increase in controlled seepage discharge (from 0.008 to 0.0098 m3/sm^3/sm3/s per unit width), a 31.7% reduction in average pore water pressure within the clay core (from 2.180 to 1.123 kPa), and a 9.3% decrease in total hydraulic head loss. Furthermore, the exit gradient remained below the safety threshold of 0.8 in 94.2% of cases, while the Factor of Safety (FOS) for downstream slope stability improved by 25.5% (from 1.45 to 1.82). Additionally, 3D arching effects resulted in an 18.4% reduction in total discharge compared to 2D analysis. Monte Carlo simulation with 10,000 iterations demonstrated a reduction in failure probability to less than 0.3%. Model calibration via the Levenberg-Marquardt algorithm confirmed high precision in replicating the dam’s long-term hydraulic behavior. This cost-effective optimization significantly enhances drainage efficiency and overall structural safety, providing a practical framework with 94.5% generalizability for the design of similar embankment dams.
Keywords: Numerical Modeling, Hydraulic Conductivity, Alluvial Layer, Seepage Flow, Dam Stability








Introduction: Clay-core earth dams are indispensable hydraulic structures for water supply, irrigation, and flood control, yet more than 35% of their historical failures stem from excessive seepage and internal erosion. The hydraulic behavior of alluvial foundation layers, characterized by high permeability and variable thickness, exacerbates these risks by promoting uncontrolled seepage, pore-water pressure buildup, and slope instability. At Nahand Dam (East Azerbaijan Province, Iran), situated on a narrow U-shaped valley with a 16 m thick alluvial layer over Eocene marls, the existing horizontal chimney drain (15 m length, 1.5 m thickness) inadequately mitigates these issues under a 35 m upstream head and 5 m downstream head. Despite advances in numerical modeling, the synergistic effects of drain geometry on seepage control, hydraulic gradients, and stability particularly in heterogeneous 3D geometries remain underexplored. This study addresses this gap by numerically evaluating a targeted 10% dimensional increase in the chimney drain (length to 16.5 m, thickness to 1.65 m) using the finite element method, with the aim of optimizing drainage efficiency, reducing seepage-related hazards, and enhancing overall dam safety for similar structures.
Materials and Methods: The numerical analysis was conducted using GeoStudio 2024 (SEEP/W and SLOPE/W modules) based on site-specific geotechnical and hydrogeological data from Nahand Dam. The 2D and 3D models incorporated realistic geometry (35.5 m dam height, 730 m crest length, central vertical clay core), material properties (Table 3: saturated hydraulic conductivities from 1×10⁻⁹ m/s for the clay core to 5×10⁻² m/s for filters/drains; Table 4: mechanical parameters calibrated via 124 triaxial tests and inverse analysis), and boundary conditions (fixed upstream head of 35 m at normal reservoir level 1607 m asl; downstream head of 5 m). A mesh of 12,800 quadratic triangular elements (2D) and 48,600 tetrahedral elements (3D) was employed, with adaptive refinement ensuring convergence (grid sensitivity: <0.3% change in seepage and pressure). Five scenarios were simulated: baseline (S0: 15 m × 1.5 m) and incremental 10–50% increases in drain dimensions, under steady-state, transient (e.g., 45-day rapid filling, 7-day sudden drawdown), and coupled hydro-mechanical conditions. Validation against 18 years of instrumentation data (22 piezometers, 6 observation wells; R² = 0.982, RMSE = 0.68 m) confirmed model fidelity (98.2% agreement). Uncertainty was quantified via global Sobol sensitivity analysis (10,000 samples) and Monte Carlo simulation (10,000 runs) on key parameters (core permeability, drain dimensions).
Results and Discussion: The 10% increase in chimney drain dimensions yielded substantial hydraulic and stability enhancements. Controlled seepage discharge rose 22.3% (0.008 to 0.0098 m³/s per unit width), facilitating efficient pore-water pressure dissipation, with average core pressures declining 31.7% (2.180 to 1.123 kPa) and total hydraulic head loss reduced by 9.3%. Exit gradients remained below the safe threshold of 0.8 in 94.2% of cases, minimizing internal erosion risk. Downstream slope factor of safety improved 25.5% (1.45 to 1.82) under steady-state conditions, with greater gains (up to 31.5%) in transient scenarios (e.g., rapid filling post-earthquake, PGA = 0.45 g). Three-dimensional arching effects reduced overall discharge by 18.4% compared to 2D models, redistributing flow toward abutments in the narrow valley. Permeability dominated over thickness (745.92% vs. 16.85% seepage impact), as confirmed by Sobol indices (S₁ core k = 0.88–0.91). Monte Carlo results indicated failure probability <0.3%, underscoring the cost-effective nature of this optimization. These outcomes align with and extend prior studies (e.g., Salmasi & Abraham, 2022; Djehiche et al., 2023), providing a validated framework for drain design in alluvial foundations.
Conclusion: This study demonstrates that a modest 10% enlargement of the horizontal chimney drain at Nahand Dam markedly improves seepage management, reduces pore pressures and hydraulic gradients, and bolsters slope stability across steady and transient regimes. The resulting enhancements 22.3% higher controlled discharge, 31.7% lower core pressures, and 25.5% greater factor of safety mitigate internal erosion and uplift risks while accounting for 3D effects. Monte Carlo analysis affirms high reliability (<0.3% failure probability), offering a practical, generalizable (94.5% applicability) blueprint for optimizing drainage in similar clay-core earth dams. These findings advocate for precise, data-driven drain modifications to ensure long-term structural integrity amid evolving hydrological demands.

Abstract Introduction
Rapseed (Brassica napus L), particularly the low erucic acid and glucosinolate cultivars known as canola, is the third largest oilseed crop in the world after soybean and oil palm. In Iran, canola cultivation covers approximately 173 thousand hectares, making it the largest cultivated area among oilseed crops. Golestan and Khuzestan provinces have the largest cultivated areas. Balanced fertilization is crucial for optimizing canola yield, especially under adverse environmental conditions. Plant tissue analysis serves as a fundamental tool for diagnosing nutrient status and exploits the principle that tissue nutrient concentration reflects soil nutrient availability. Advanced diagnostic methods, such as deviation from optimum percentage (DOP) and nutrient balance index (NBI), provide quantitative measures of nutrient adequacy and imbalance. The DOP method ranks nutrient deficiencies by comparing observed tissue concentrations with those in high-yielding populations. Meanwhile, the NBI integrates multiple nutrient statuses into a single measure (Σ|DOP|) and provides a comprehensive assessment of overall nutrient health.
Materials and Methods
The study was conducted in four provinces: Alborz, Markazi, Golestan, and Ardabil (Moghan region), to reflect the diverse agro-ecological conditions of the country. Thirty farms were randomly selected in each province.
Alborz province (Karaj region) is located at latitudes 35°48'N and 51°10'E. Markazi province (Arak city) is located at latitudes 34°5'30'N and 49°41'30'E. East Golestan Province (Gonbad Kavus region) is located at coordinates 37°16'N and 55°12'E, while Ardabil Province (Parsabad and Moghan regions) is located at coordinates between 39°12'N and 39°42'N and 47°10'E and 48°21'E.
Soil samples were collected from the fields before planting. Plant tissue samples were taken at the biganing of stem elongation stage (two-digit growth code 30), which is a sensitive stage for identifying and eliminating nutrient deficiencies before canola flowering. Plant samples were collected as whole plants from 20 random points per hectare, and 20 plants were sampled from each point. Total nitrogen (N), phosphorus (P), potassium (K), and micro nutrients zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), and boron, were measured in plant tissue. Grain yield was measured at maturity. To assess nutrient status and identify yield-limiting factors, the key diagnostic index, deviation from optimal percentage (DOP), quantifies the deviation in nutrient concentrations from the optimal values observed in high-yielding populations. The NBI index was also used in this study.
Results and Discussion
In terms of soil properties, there was significant variation in pH, salinity, organic carbon, and nutrient availability across the studied provinces.
In Alborz province, the average organic carbon content was low (0.81%) and the frequency of nutrient deficiencies was high, including nitrogen (N, 73%), phosphorus (P, 47%), potassium (K, 20%), sulfur (S, 87%), magnesium (Mg, 37%), iron (Fe, 83%), copper (Cu, 20%), zinc (Zn, 50%), manganese (Mn, 43%), and boron (B, 60%). In Markazi Province, with an average salinity of 1.47 dS/m, severe deficiencies of nitrogen (90%), phosphorus (75%), and potassium (37%) were observed. In Golestan Province, non-saline soils in this region with an average organic carbon percentage of 1.4% showed deficiencies of nitrogen (27%), phosphorus (94%), potassium (32%), magnesium (100%), iron (32%), copper (22%), manganese (31%), and zinc (81%). In Ardabil Province, high clay content (40%) and salinity (2.4 dS/m) led to deficiencies of phosphorus (50%), potassium (1%), sulfur (99%), magnesium (99%), iron (50%), copper (3%), zinc (87%), and manganese (10%).
DOP standards for nutrient concentrations in canola shoots during stem elongation were determined as follows: nitrogen 3.61%, phosphorus 0.46%, potassium 2.8%, sulfur 0.513%, magnesium 44.00%, calcium 1-2%, iron 226 mg/kg, copper 1.8 mg/kg, manganese 78.5 mg/kg, zinc 45.8 mg/kg, and boron 54 mg/kg.
The nutrient balance index (NBI), calculated as the sum of absolute DOP values, was inversely correlated with yield, confirming that greater nutrient imbalances resulted in reduced yield. Statistical analyses confirmed that NBI thresholds between 133 and 146 corresponded to significant yield reductions (p<0.01). based on these thresholds, yield decreased by 12 to 18% for each unit increase in NBI. It is noteworthy that when NBI exceeds a certain threshold (NBI breakpoint) (BPC), yield reduction becomes more evident. Below this threshold, yield is less affected by NBI. Alborz province had the highest BPC (146), followed by Ardabil (139), Markazi (138), and Golestan (133) provinces, respectively. Farmers and advisors can use this range as a guide for fertilizer recommendations.
Conclusion
This study shows that the variability of canola yield in agro-ecological regions of Iran is primarily due to the deficiency of region-specific nutrients, especially phosphorus and zinc, combined with soil alkalinity, low organic carbon, and mineralogical characteristics. By implementing region-specific nutrient management strategies, yield gaps can be closed, and sustainability in semi-arid oilseed systems can be promoted. The Balance Index integrates vital nutrient ratios (such as phosphorus:zinc, magnesium:potassium) to detect imbalances.

Abstract Introduction
Cadmium (Cd) and lead (Pb) contamination of calcareous soils can restrict wheat production in arid and semi-arid regions. High pH and calcium carbonate reduce metal solubility but cannot fully prevent root uptake or food-chain entry. Both metals impair nutrient acquisition, damage chloroplasts and membranes, reduce photosynthesis, and promote ROS production, causing oxidative damage and redox imbalance. Thiols mediate plant responses to metal stress. Cysteine supplies sulfur for glutathione synthesis, while glutathione supports redox buffering, antioxidant reactions, metal detoxification, and phytochelatin production. Evidence for simultaneous foliar application of cysteine and glutathione under Cd–Pb stress in wheat grown in calcareous soil remains limited. This study examined individual and combined thiol sprays on wheat growth, oxidative damage, glutathione redox status, and Cd and Pb accumulation under Cd–Pb co-contamination.
Materials and Methods
A pot experiment was conducted in a greenhouse at the Faculty of Agriculture, Ferdowsi University of Mashhad. Calcareous clay loam soil was collected from the 0–30 cm layer of agricultural land near Sabzevar, Iran. Soil pH was 7.89 (1:2.5 soil:water), electrical conductivity 2.53 dS m⁻¹, organic matter 1.03%, and calcium carbonate equivalent 24.55%. DTPA-extractable Cd and Pb were 0.12 and 1.5 mg kg⁻¹, respectively, representing low background levels before contamination.
The experiment used a randomized design with five treatments and three replications (15 pots): control without metals, sprayed with deionized water; HM, with 15 mg Cd kg⁻¹ soil and 300 mg Pb kg⁻¹ soil; HM+Cys, with 0.41 mM L-cysteine foliar spray; HM+GSH, with 2 mM reduced glutathione; and HM+Cys+GSH, receiving 0.41 mM cysteine plus 2 mM glutathione. L-cysteine and reduced glutathione (≥99% purity) were obtained from Sigma–Aldrich.
Cadmium and Pb were added as Cd(NO₃)₂ and Pb(NO₃)₂ to 5 kg soil per pot. Nitrate input was identical among contaminated treatments and considered a common HM component. Soils were mixed and incubated for four weeks near field capacity before planting. Wheat seeds (Triticum aestivum L. cv. Falat) were disinfected in 5% sodium hypochlorite for 10 min, rinsed three times with deionized water, and sown in pots 23 cm in diameter and 21.5 cm high. Eight seeds per pot were thinned to five plants after establishment. Foliar treatments were applied at tillering, stem elongation, and booting; controls received equal volumes of deionized water.
Plants were harvested about 70 days after sowing. Shoot dry biomass was measured after oven drying at 70 °C for 72 h. Total chlorophyll was determined in 80% acetone extracts at 663 and 645 nm following Lichtenthaler (1987). MDA and H₂O₂ were measured at 532 and 390 nm, respectively. GSH and GSSG were assayed in 2% metaphosphoric acid extracts using glutathione reductase, NADPH, DTNB, and 2-vinylpyridine; the GSH/GSSG ratio assessed redox status.
Root and shoot samples were wet-digested with concentrated HNO₃ and H₂O₂, and Cd and Pb concentrations were determined by flame AAS (Analyst 800, PerkinElmer). Oxidative stress index, total thiol pool, tolerance index, chlorophyll protection efficiency, and transfer factor were calculated. Data were analyzed by one-way ANOVA, and means were compared using Duncan’s multiple range test.
Results and Discussion
Combined Cd and Pb stress substantially reduced wheat growth. Shoot dry biomass declined from 12.50 g pot⁻¹ in the control to 7.10 g pot⁻¹ under HM, a 43% reduction. Total chlorophyll decreased from 2.10 to 1.10 mg g⁻¹ fresh weight (47%). All thiol treatments improved both traits. Shoot biomass reached 8.60, 9.60, and 11.00 g pot⁻¹ in HM+Cys, HM+GSH, and HM+Cys+GSH, respectively, while chlorophyll increased to 1.50, 1.70, and 1.90 mg g⁻¹ fresh weight. Tolerance index and chlorophyll protection efficiency showed similar responses. The combined treatment produced the highest values among metal-stressed plants, although neither trait fully reached control values. Oxidative damage increased sharply under HM. MDA increased from 15.00 to 40.00 nmol g⁻¹ fresh weight, while H₂O₂ increased from 4.30 to 12.20 µmol g⁻¹ fresh weight. Cysteine, glutathione, and their combination reduced both indices. MDA concentrations were 32.00, 27.00, and 22.00 nmol g⁻¹ fresh weight in HM+Cys, HM+GSH, and HM+Cys+GSH, respectively; corresponding H₂O₂ values were 9.20, 7.50, and 6.20 µmol g⁻¹ fresh weight. The OSI increased from 0.05 in the control to 0.37 under HM. Cysteine reduced it to 0.17, whereas glutathione alone and the combined treatment both reduced it to 0.10. Therefore, the combined treatment did not exceed glutathione alone for this index, showing that treatment superiority differed among traits.
Cd and Pb strongly affected glutathione redox status. GSH declined from 85.30 to 32.90 nmol mg⁻¹ protein under HM, whereas GSSG increased from 15.20 to 31.00 nmol mg⁻¹ protein. Accordingly, the GSH/GSSG ratio declined from 5.61 to 1.07. Thiol application improved redox status in all treated plants. HM+GSH produced the highest GSH concentration, whereas HM+Cys+GSH produced the highest GSH/GSSG ratio. Under the combined treatment, GSH reached 62.70 nmol mg⁻¹ protein, GSSG decreased to 10.50 nmol mg⁻¹ protein, and the GSH/GSSG ratio reached 6.00. This ratio differed significantly from all stressed treatments but not from the control, indicating near-control redox restoration. Thiols also reduced Cd and Pb accumulation. Under HM, Cd concentrations were 19.0 mg kg⁻¹ in roots and 7.6 mg kg⁻¹ in shoots; under HM+Cys+GSH, they decreased to 10.4 and 4.0 mg kg⁻¹, respectively. Root Pb declined from 25.5 to 12.5 mg kg⁻¹, while shoot Pb declined from 9.8 to 5.5 mg kg⁻¹. Cysteine and glutathione alone also lowered both metals, although differences between HM+GSH and HM+Cys+GSH for shoot Cd and Pb were often not significant.Transfer factors for Cd and Pb remained below 0.5, indicating limited root-to-shoot translocation. Roots retained a substantial proportion of absorbed metals, reducing but not eliminating accumulation in shoots.
Conclusion
Cd–Pb co-contamination reduced wheat shoot biomass and chlorophyll, increased MDA and H₂O₂, and disrupted glutathione redox balance. Foliar cysteine and glutathione alleviated these effects. Their combined application produced the strongest response for most growth, oxidative, redox, and tissue-metal traits, improving biomass and chlorophyll, reducing oxidative damage, restoring GSH/GSSG to a control-comparable value, and lowering Cd and Pb in roots and shoots. Transfer factors remained below 0.5, indicating limited root-to-shoot translocation. Field validation and grain-metal measurements are required before recommending this treatment for food production.

Abstract Introduction: Mycorrhizal symbiosis, particularly arbuscular mycorrhiza, is recognized as one of the most widespread and beneficial interactions between plants and soil microorganisms and has been extensively studied. This symbiosis plays a significant role in improving plant nutritional status, enhancing resistance to both biotic and abiotic stresses, reducing the impact of certain pathogens, and promoting synergistic interactions with other beneficial microbial communities. Ultimately, these effects contribute to improved crop health and productivity. One of the most important benefits of this association is the enhancement of plant nutrition. Mycorrhizal plants acquire nutrients either directly through their roots or indirectly via the hyphal network of symbiotic fungi. The predominance of either pathway depends on a complex set of biochemical and molecular mechanisms within the common symbiosis pathway, as well as phosphorus availability, plant phenotypic traits (especially root characteristics), and environmental conditions. Despite its importance, the degree of mycorrhizal dependency varies among plant species and cultivars. Mycorrhizal dependency is defined as the extent to which a plant relies on mycorrhizal fungi to achieve optimal growth or yield. It is determined by the interaction between plant genotype and phenotype in combination with environmental factors.
Mycorrhizal symbiosis is the result of a complex molecular dialogue between plant and fungus, involving the exchange of signals at cellular, molecular, and genetic levels. In the early stages of symbiosis, plants secrete compounds such as strigolactones from their roots, which stimulate spore germination and hyphal branching. This is followed by fungal signalling molecules, including chito-lipo-oligosaccharides, which act as key signals in the initiation and regulation of arbuscular mycorrhizal symbiosis. Disruption in this shared signalling pathway can lead to failure of symbiosis establishment or reduced mycorrhizal dependency.
Under high nutrient conditions, particularly high phosphorus availability, plant secretion of strigolactones is typically reduced. This illustrates how excess soil phosphorus can interfere with the common symbiosis signalling pathway and thereby decrease mycorrhizal dependency. The synthesis and secretion of strigolactones are regulated by the upregulation of genes such as D27, CCD7, CCD8, and MAX1.
Recent advances in plant molecular biology and genetics have identified a set of genes involved in the common symbiosis pathway that play essential roles in fungal signal recognition, activation of cellular responses, and the formation of fungal structures such as arbuscules. These genes, including SYMRK, CCaMK, and CYCLOPS, will be discussed in detail later. Depending on the upregulation or downregulation of these genes in the plant–fungus symbiotic pathway, a higher or lower degree of mycorrhizal dependency can be expected, respectively.


Materials and Methods: This analytical review integrates findings from researchers in this field by utilizing up-to-date studies on the intensity of plant–fungus symbiosis and the degree of mycorrhizal dependency from morphological, physiological, biochemical, and especially molecular dimensions. These studies are accessible through major international databases, including Web of Science and Scopus. In addition, Google Scholar provides an open-access platform for identifying recent publications, while specialized resources such as ScienceDirect, SpringerLink, and Taylor & Francis offer valuable journal articles, book chapters, and authoritative reference works related to mycorrhizal dependency and the underlying mechanisms involved, particularly from a molecular perspective.
Results: The results of numerous studies indicate that the establishment of symbiosis between plants and arbuscular mycorrhizal fungi requires a series of complex physiological, biochemical, and molecular interactions. This process is initiated by the secretion of Myc-LCO signalling molecules by the fungus, which are subsequently recognized by specific receptors in plant roots, including SYMRK (DMI2). Following recognition, the common symbiosis signalling pathway is activated, and the release of calcium ions (Ca²⁺) through DMI1 generates rhythmic calcium oscillations within plant cells. These oscillations function as informational codes that are decoded by the calcium and calmodulin-dependent protein kinase (CCaMK). The calcium signals are then translated into molecular responses, leading to the activation of the transcription factor CYCLOPS and the regulation of symbiosis-related gene expression, ultimately resulting in arbuscule formation. Any disruption or interruption in this signalling pathway may prevent arbuscule development, particularly in non-host plants. The degree of plant dependence on mycorrhizal fungi is influenced by a range of factors, including plant, fungal, and environmental characteristics. Among environmental factors, abiotic stresses such as drought play a critical role. Under drought conditions, the influx of Ca²⁺ into the plant cell cytosol decreases, leading to disturbances in cellular ion homeostasis. However, the presence of mycorrhizal fungi enhances the expression of calcium-sensing and signalling genes, including CBLs, CDPKs, and MAPKs, thereby activating Ca²⁺-dependent signalling pathways. This process regulates and reinforces the increase in cytosolic Ca²⁺ concentration, which acts as an important secondary messenger during the establishment and maintenance of mycorrhizal symbiosis. Furthermore, numerous studies have demonstrated a significant relationship between mycorrhizal dependency and root morphological characteristics. In general, plant species possessing a magnolioid root architecture exhibit a greater degree of dependence on arbuscular mycorrhizal fungi than species with non-magnolioid root systems.
Conclusions: Although many plant species can establish symbiosis with mycorrhizal fungi, the degree of dependency and effectiveness of this association varies considerably. These differences are largely determined by the complexity of signalling pathways and the regulation of symbiosis-related genes. A deeper understanding of the underlying molecular and cellular mechanisms is essential for improving mycorrhizal symbiosis, although significant challenges remain in its practical application.

Abstract Introduction: Soil salinity in arid and semi-arid regions is one of the important factors that limits crop production, and affects plant yield through various mechanisms. Chlorophyll destruction and reduction of leaf area due to high sodium concentration leads to a decrease in photosynthesis. The application of humic acid and amino acid with hormonal effects and adjustment of nutrients has been suggested to reduce salinity stress. The experiment aimed to investigate the effect of plant growth biostimulants and salinity levels on the growth indices of two canola cultivars in greenhouse condition.
Materials and Methods: This study was carried out as a factorial study based on a completely randomized design with three replications. The three experimental factors included: 1) salinity factor in three levels (0.571, 4, and 8 dS m-1), 2) canola cultivars in two levels (Hyola 50 and Dalgan), and 3) types of plant growth biostimulants in four levels (amino acid, humic acid, a combination of these two biostimulants, and a control treatment with no biostimulants application). Before the flowering stage (8 weeks after planting), the plants were harvested and some morphological traits including plant dry weight, root dry weight, and the concentration of calcium, sodium, and potassium in the shoot were measured.
Results and Discussion:
Based on the results, the cultivar Hyola 50 (8.35 g plant-1) had a significantly higher shoot dry weight than the cultivar Dalgan (7.58 g plant-1). The reduction in shoot dry weight at a salinity level of 8 dS m-1 was 19.3% compared to the treatment of 0.571 dS m-1. At salinity levels of 0.571 and 4 dS m-1, there was no difference between the effects of biostimulant treatments compared to the control (without biostimulants). But at a salinity level of 8 dS m-1, the shoot dry weight of the humic acid treatment (7.26 g plant-1) was significantly higher than the control treatment (16.6 g plant-1) (17.9% difference). The effect of humic acid application on leaf area (748 cm2 plant-1) was greater than that of amino acid foliar application (670 cm2 plant-1). With an increase in salinity level to 8 dS m-1, the dry weight of roots decreased. The highest dry weight of the root in the Dalgan cultivar at 8 dS m-1 was obtained in the combined treatment (0.607 g plant-1) and for the cultivar Hyola 50 in the combined treatment and amino acid (0.607 g plant-1). There was a significant difference in root dry weight between salinity of 4 dS m-1 (0.703 g plant-1) and 8 dS m-1 (0.543 g plant-1). The root dry weight of the plant was more affected by salinity stress than the shoot dry weight. In both canola cultivars, at a salinity level of 8 dS m-1, the chlorophyll index (SPAD) increased compared to a salinity level of 0.571 dS m-1 (4.6% increase in Dalgan cultivar and 9% in Hyola 50 cultivar). The shoot potassium concentration of the Dalgan cultivar (11.6%) was significantly higher than that of the Hyola 50 cultivar (92.5%), but the amount of uptake was higher in Hyola 50 cultivar (492.0 versus 459.0 g plant-1). At 8 dS m-1 salinity, the furthest potassium to sodium concentration ratio of the Dalgan cultivar was obtained with amino acid and humic acid treatment (4.87) and with the Hyola 50 cultivar with the humic acid treatment (4.21). At 8 dS m-1 salinity, the calcium to sodium concentration ratio of the Dalgan cultivar was obtained from the amino acid and humic acid treatment (12) and for the Hyola 50 cultivar from the humic acid, amino acid, and combined treatment (11). At a salinity level of 8 dS m-1, combined treatment of biostimulant in both Dalgan (1236 meq l-1) and Hyola 50 (250 meq l-1) cultivar had the highest amount of soil-soluble chlorine. This treatment may have reduced the absorption of chlorine ions by the plant. Shoot dry weight had the highest correlation with root dry weight and leaf area (0.58**). Shoot dry weight had the negative correlation with plant sodium concentration (-0.27**). The negative effect of soil-soluble sodium concentration on root dry weight (-0.39**) was greater than on shoot dry weight (-0.27**).
Conclusion: The positive effect of the application of growth biostimulants was observed through improving potassium absorption and improving the ratio of calcium and potassium to sodium concentrations in the shoot. In saline conditions (8 dS/m), the recommended phosphorus fertilizer for Dalgan variety must be 23.6%, and for the Hyola 50 variety, 10% more phosphorus fertilizer than in non-saline conditions. The application of Hyola 50 and humic acid as fertigation in saline conditions is recommended for canola.

Abstract Abstract In order to estimate the freezing depth and developing a simple and rational relationship between air temperatures at the screen and soil temperature at different depths a study was conducted during 1386. The maximum and minimum daily air temperatures (2 meter above ground) and the soil temperature at 5, 10, 20, 30, 50 and 100 centimeter depths were measured at 12 stations of Khorasan Razavi province. Functional relationships were developed between air and soil temperatures for each station. Also, soil freezing depths were estimated by four standard methods. The estimated depths were compared with actual freezing depths which were measured during the year of observation. The results showed that the Finnish and Norway methods were more reliable than U.S. and SNipll – 15 – 74 methods. Key words: Air temperature, Soil temperature,Freezing depth

Abstract        Long term trend analysis of meteorological variables has a great importance in climate change detection studies. The purpose of this study was to assess changes in relative humidity and dew point temperature over the period 1973-2003. Monthly data of relative humidity and dew point temperature of 22 synoptic stations of Iran were obtained from Iran Meteorological Organization (IRIMO). These stations represent different climates of the country based on De Martonne climatic classification. All seasonal and annual series have been checked for normality with the Kolmogorov-Smirnov test. Time trends of both variables were analyzed using parametric and non-parametric techniques (Least square linear regression, Mann-Kendall and rho-Spearman correlation coefficient).Based on the results of Mann-Kendall test, the most significant increasing trend of both variables exists in summer season and the least trend of relative humidity was observed in winter season. The most and least increasing trend of dew point temperature was observed in spring and autumn respectively. Using rho-spearman correlation coefficient, the most significant decreasing trend of relative humidity was observed in annual and spring time series. Parametric test of regression analysis revealed no specific trend in dew point series, but all seasonal series of relative humidity showed trend. In general, the decreasing trend of series was more that increasing trend. The results indicated that no specific climatic pattern of trends can be suggested.

Abstract Introduction: In Golestan province, despite the lack of water resources, traditional rice cultivation, a crop with high water consumption, is increasing due to economic justification. This issue has become one of the main problems of the province's agricultural sector in recent years. In order to prepare the planting bed (puddled transplanting) in the traditional method of rice production, a significant amount of irrigation water is used before planting the seedlings in the main land. Moreover, the plant is in the water during the growing season, which causes high water losses by surface water evaporation and deep penetration. Rice direct seeding cultivation is a method that has been considered in the world for various reasons, including higher water productivity. Currently, reports indicate that more than 50% of groundwater resources are extracted and allocated annually for rice cultivation in the region investigated. In general, field information and observations indicate that the level of paddy cultivation is increasing in the province. In the past few decades, agricultural policymakers have sought to restrict and ban rice cultivation in the country, except in Gilan and Mazandaran provinces. The rationale behind this decision is high water consumption, declining groundwater aquifers and long-term instability of water resources. The developed strategy did not work effectively, as it did not consider the benefits of the farmers in the short run. The increasing trend in the area under paddy fields from 1995 to 1500 hectares per year shows the unsuccessfulness of this up-to-down strategy.
Materials and Methods: A field experiment was conducted to investigate the effect of rice cultivation and irrigation methods on yield, water consumption and water productivity over two rice cropping seasons (2019–2020) in northern Iran (Gorgan Agricultural Research Station). Irrigation method as the main factor in four levels (permanent flooding, intermittent as wet and dry, sprinkler, tape) and cultivation method in three levels (direct seed in dry bed, non-puddled transplanting and traditional transplanting) in the form of a strip design. The plot was based on a randomized complete block design with three replications. The applied water, yield and some yield components and water productivity were measured and calculated during the growing seasons.
Results and Discussion: The results showed that in all irrigation methods, yield was significantly reduced by changing the traditional seeding transplanting to dry seed. The amount of water applied in sprinkler and drip irrigation methods from traditional seedlings was significantly reduced as compared to direct seed seeding. Dry seed cultivation, however, consumed more water than traditional transplanting in the flood irrigation treatments (wet and dry and permanent). The highest yield (8206 kg/ha) was obtained for traditional seedling cultivation by flood irrigation, and no significant difference was observed between the yields for the other irrigation methods. In general, changing the irrigation systems had a greater effect on water consumption than changing the rice cultivation method. In addition, changing the cultivation method had a greater effect on changing the type of irrigation systems. In traditional transplanting cultivation, the yield decreased by about 14, 9 and 11%, respectively, by changing the irrigation systems from permanent flood irrigation to sprinkler, wet and dry, and drip irrigation. The highest water use was observed for flood irrigation method in direct seeding (12490 m³/ha) and direct transplanting (11967 m³/ha).
Conclusion: Currently, farmers cultivate rice by transplanting in padded land irrigated by flooding techniques in Golestan province, which results in high water consumption (about 13,000 m³/ha). By changing the irrigation method from flood irrigation to drip for traditional transplanting cultivation, water consumption decreased by about 39% and as a result water productivity increased by about 22%, albeit a 11% reduction in yield occurred. With the conversion of traditional transplanting seedling by flood irrigation to non-puddled transplanting by drip irrigation, the yield decreased by about 24% and the amount of water by about 45%, and water productivity in this case reached 0.9 kg/m³. This can be considered as the best alternative for conserving both water resources and production. If only reducing water consumption is the main priority (regardless of yield reduction), the best treatments are drip irrigation with direct seeding, non-puddled transplanting and then traditional seedling, respectively. If there is a sprinkler irrigation system in the field, this option is given priority in the direct seeding and non-puddled transplanting. If changing the irrigation system is not considered, the use of intermittent irrigation (as a wet and dry) with non-puddled transplanting, traditional methods and direct seeding are preferred, respectively.

Abstract Introduction: Nowadays, the issue of climate change and its related problems are fundamental crisis in water resource management. On the other hand, considering that groundwater is the most important water resources, determination of the effects of climate change on groundwater and estimation the amount of their recharge will be necessary in the future. Materials and Methods: In this research, to analyze the effects of climate change scenarios on groundwater resources, a case study has been applied to the Sefid Dasht Plain located in Chahar Mahal and Bakhtiari Province in Iran. One of the three Atmospheric-Ocean General Circulation Models (AOGCM) which is called HadCM3, under the emission scenarios A2 and B1 is used to predict time series of climate variables of temperature and precipitation in the future. In order to downscale the data for producing the regional climate scenarios, LARS-WG model has been applied. Also, IHACRES model is calibrated and used for simulation of rainfall - runoff with monthly temperature, precipitation and runoff data. The predicted runoff and precipitation production in future have been considered as recharge parameters in the ground water model and the effects of climate change scenarios on the ground water table has been studied. To simulate the aquifer, GMS software has been used. GMS model is calibrated in both steady and unsteady state for one year available data and verification model has been performed by using the calibration parameters for four years. Results and Discussion: Results of T- test shows that LARS-WG model was able to simulate precipitation and temperature selected station appropriately. Calibration of IHACRES model indicated the best performance with τw=6 و f=7.7 and the results shows that IHACRES model simulated minimum amount of runoff appropriately. Although it didn’t simulate the maximum amount of runoff accurately, but its performance and Nash coefficient is acceptable. Results indicate that changes of monthly precipitation in the future period are less than the base period in both scenarios A2 and B1. Precipitation increases about 26 and 33 percent under the scenario B1 and A2 respectively in the future compared to the base period. The monthly average temperature in the future compared to monthly average temperature in the base period has been increasing in both scenarios about 1 degree. Root Mean Square Error criteria for aquifer simulation was 1.6 in steady state and 1.9 in unsteady state. This result indicates that the aquifer has been accurately simulated. Assuming the same rate of pumping wells in the future period and in the base period, despite the increasing of recharge in the future period, water levels decrease notably in the central plains due to exceeding operation. At the end of the period (year 2035) the amount of cumulative groundwater recharges in the scenario A2 compared to scenario B1 increases about 10 cubic meters per second, which shows that the impacts of climate change in the A2 scenario compared to the B1 scenario is more. Conclusion: Study the impact of climate change is important in our country because the major uses of water supply of groundwater. Enormous use of this resource has been defected aquifer problematically. So, it is necessary to survey impacts of climate change in future period on recharge and water levels aquifer by modeling and simulation. It is useful to predict the future conditions of groundwater. Although the recharge increases in future period, but with respect to high rate of groundwater use, it is impossible to achieve an equivalent level of aquifer without any planning. We need to control on pumping well and treatment of aquifer such as underground water dam, artificial recharge and etc. results of this research can be evaluated by other climatic scenarios, downscaling models and rainfall-runoff models. The results of this research, considerably helps to assess the effects of climate change scenarios on ground water resources as well as its proper planning and management.

Abstract Introduction: Delineating landscape into homogenous units is fundamental to managing resources and delivering sustainable development. The importance of this has long been recognized as a critical issue in various studies and it has been examined from different aspects. In soil mapping, the geopedologic approach is used for landscape classification, which was defined by Zinck (1989). This approach differentiates landscapes into landforms to increase the purity of soil map units. Therefore, the aim of this study was preparing geopedologic maps of the study area on the level of landform phases intending to make more homogeneous soil units.
Materials and Methods: Honam sub-basin in Lorestan province is one of the most important agricultural areas in the Karkheh River watershed. Soil moisture and temperature regimes of the area were Xeric and Mesic, respectively. After a primary interpretation, a geopedology map of the study area at the landform level was prepared according to the geopedologic approach. After soil surveying, 31 profiles were excavated, described, and sampled in the largest delineation of this map. Ultimately, this landform unit was differentiated to the landform phase units using morphometric features and normalized difference vegetation index. Pedodiversity index was computed for each landform phase unit to investigate the credibility of the geopedological approach for this unit. The conditional probability of each soil family was also measured in each landform phase unit to compare statistical differences between landform phase units. Furthermore, statistical comparisons were made between the Shannon indices of each unit.
Results and Discussion: The soils of the study area were classified into seven soil families according to Soil Survey Staff (2014). Based on the geopedology map, this area includes two landscapes of Piedmont plains and valleys. These two landscapes were differentiated to 6 and 3 relief/molding, respectively. Geologically, the study area has 5 lithologic units. Finally, 22 landform units were identified in this area. The area of the widest landform with the code of Pi461 was 1223.35 ha. With individual use of NDVI, TRI, and aspect map, this landform unit was differentiated into 3 phases, and with the use of these 3 maps collectively, 11 phases were differentiated. The results showed landform map unit of Pi641 with 31 soil profiles and 7 soil families has the highest value of diversity indices, such as 1.59 for the Shannon index. In addition, this map unit is a compound map unit consisting of several soils, where the highest probability of observing soils is related to soils A and B with 32.5% probability. By differentiating this landform unit into phases, the Pi461 map unit is separated into smaller units that are more homogeneous. For example, when it is separated according to the vegetation characteristics, the three phases Pi4611 (N), Pi4612 (N), and Pi4613 (N) were differentiated that have medium, low, and high vegetation, respectively. In this case, Pi4612 (N) map unit with 75% probability of soil C observation and Pi4613 (N) map unit with 87.50% probability of soil B observation are two homogeneous map units. The Shannon index of these two units is 0.56 and 0.37, respectively, which indicates the purity of these map units. The results also showed that diversity indices and conditional probabilities, respectively, were decreased and increased in most of the landform phase map unit compared to the landform map unit. The use of normalized difference vegetation index compared to other environmental features has been effective in separating the landform phase units and preparation of homogeneous map units. So, the most probability of observing the dominant soils of the study area increased from 32.25% in the landform unit to 52.63, 75.75, and 87.50% in the landform phase unit, and the Shannon index decreased from 1.59 in the landform unit to 1.36, 0.56, and 0.37 in the landform phase units. The use of other environmental features to increase the purity of the landform phase map unit is suggested in future studies.
Conclusion: Results of using geopedological approach at landform level in the study area showed that this level is useful at highest levels of soil classification (from order to great group), but due to the complex nature of soils at lower levels of classification (family and soil series) does not have enough efficiency. Therefore, for improving the geopedology method accuracy and to present more uniform map units at lower levels of classification, landform phase maps were presented according to the environmental characteristics of the selected landform. The statistical comparisons between Shannon indices calculated for each map unit in the landform phase map showed a significant difference at the 90% probability level between most of the units, which indicates an increase in the purity of these units at the soil family level.

Abstract Introduction: Soil Hydraulic conductivity is considered as one of the most important hydraulic properties in water and solutionmovement in porous media. In recent years, variousmodels as pedo-transfer functions, fractal models and scaling technique are used to estimate the soil saturated hydraulic conductivity (Ks). Fractal models with two subset of two (solid and pore) and three phases (solid, pore and soil fractal) (PSF) are used to estimate the fractal dimension of soil particles. The PSF represents a generalization of the solid and pore mass fractal models. The PSF characterizes both the solid and pore phases of the porous material. It also exhibits self-similarity to some degree, in the sense that where local structure seems to be similar to the whole structure.PSF models can estimate interface fractal dimension using soil pore size distribution data (PSD) and soil moisture retention curve (SWRC). The main objective of this study was to evaluate different fractal models to estimate the Ksparameter. Materials and Methods: The Schaapetal data was used in this study. The complex consists of sixty soil samples. Soil texture, soil bulk density, soil saturated hydraulic conductivity and soil particle size distribution curve were measured by hydrometer method, undistributed soil sample, constant head method and wet sieve method, respectively for all soil samples.Soil water retention curve were determined by using pressure plates apparatus.The Ks parameter could be estimated by Ralws model as a function of fractal dimension by seven fractal models. Fractal models included Fuentes at al. (1996), Hunt and Gee (2002), Bird et al. (2000), Huang and Zhang (2005), Tyler and Wheatcraft (1990), Kutlu et al. (2008), Sepaskhah and Tafteh (2013).Therefore The Ks parameter can be estimated as a function of the DS (fractal dimension) by seven fractal models (Table 2).Sensitivity analysis of Rawls model was assessed by making changes)±10%, ±20% and±30%(in input parameters (porosity, fractal dimension and the intake air suction head).Some indices like RMSE, AIC and R2 were used to evaluate different fractal models. Results and Discussion: The results of the sensitivity analysis of Rawls - Huang model, showed the least sensitivity to changes in porosity and suction entry air and the most sensitivity to changes in fractal dimension. The saturated hydraulic conductivity is underestimated by increasing the fractal dimension in Rawls - Huang model. The high sensitivity of the combined model to changes in fractal dimension, is considered as one of the model limitations.In other words, fractal dimension underestimation increased the error related to the hydraulic conductivity estimation. Sensitivity analysis of Ks regression model was done among parameters like bulk density, dry density, silt, sand, fractal dimension of particle size and porosity. Results showed less sensitivity to fractal dimension and porosity. The highest RMSE was 0.018 for fractal dimension and porosity (in the range of ±30% changes). The results showed that the amount of clay in the estimation of fractal dimension is of crucial importance. Statistical analyzes indicated the high accuracy of the PSF models based on soil texture data.Error indices showed the high accuracy of Rawls and three-phase fractal (pore- solid- fractal) models combination in estimating the Ks value. The results suggest that Huang and Zhang model, with the highest correlation, the least Root Mean Square Error and the least Akaike criteria among the studied fractal models for estimation of the Ks values. Fuentesand Hunt models, overestimated soil saturated hydraulic conductivity. Fuentes et al. (1996) as an experimental fractal model to estimate the saturated hydraulic conductivity indicatedvery poor results. Bird model had higher error values compared with the best model, (RMSE =0.73). This model fit well with the measured values compared to Sepaskhah and Taylor models particularly at low Ksvalues. Taylor's two-parameter model, which is similar to the Brooks - Corey and the Campbell model, was inserted in the fourth priority. The RMSE values of Sepaskhah and Taylor models were 0.62 (cm/h) and 0.55(cm/h) respectively. The fractal dimension is a function of soil texture. Heavy soils resulted in a larger fractal dimension and less hydraulic conductivity. Therefore, the Huang-Zhang model as a result of clay value using model (lower values for Ks), had a close fit with the measured data in probability distribution. Conclusions: The results showed that the soil clay percent had a significant role in fractal dimension calculation.

Abstract Introduction: Inter-basin water transfer affects the environment, culture and economy of donor and recipient basin. In this regard, one of the most important aspects are the positive and negative effects on the quality of groundwater in the recipient basin.  Spatio-temporal changes of groundwater quality as the results of inter-basin water transfer, plays an important role in water resources management. Thus, this study attempts to investigate the temporal trends of groundwater quality parameters using Mann-Kendall test and Sen's slope estimator. In addition, spatial changes of groundwater quality and the effects of inter-basin water transfer were studied.
Materials and Methods: In this study, non-parametric methods and interpolation models were used to evaluate the  spatio-temporal patterns of groundwater quality parameters in the Yazd-Ardakan plain. Mann-Kendall nonparametric test and Sen's slope were used to examine the temporal trends in the span of 2000 to 2020. The interpolation models and groundwater quality index (GQI) were used to study the spatial patterns and classify the quality of groundwater. The assessment of quality parameters of all studied wells including Ca²⁺, Mg²⁺, Cl^-, Na⁺, SO₄^2- and TDS were studied in equal time periods. Groundwater quality measurements were performed twice a year using a volumetric method, one in spring and the other one in autumn. The World Health Organization (WHO) standard was considered to compare values of different parameters in the plain.
Results and Discussion: A decreasing trend was observed in SO₄^2-, Na⁺ and TDS parameters in most wells and there was an increasing trend for Ca²⁺, Mg²⁺ and Cl^- parameters. Considering WHO classification standard, all the studied parameters were in the allowable ranges except TDS. The parameter ranking showed that TDS, Cl^- and Mg²⁺ had the greatest impact on the quality of aquifer groundwater. The Mg and TDS parameters had the highest and the lowest changes, respectively during 2000 to 2020. Results of the GQI showed that the total quality of the Yazd-Ardakan aquifer was in the moderate class and acceptable because of relatively large decrease in the groundwater in the span of the studied period. However, the decrease in groundwater quality was negligible. Changes of the quality map showed that the most negative quality changes were related to the Yazd, Taft, Meybod, Ardakan and northern regions (Chah-Afzal desert). This indicates high groundwater pumping in these areas and being located near the desert area. The most positive quality changes belonged to the central and southern part of the aquifer.
Conclusion: Comparison of the interpolation models showed that the geostatistical methods can show better results than the definitive methods in zoning groundwater quality parameters. The Kriging and IDW models were the best models and consistent with the results of the research. The quality of groundwater was acceptable, while the reduction in quality was very low and negligible in the Yazd-Ardakan aquifer during the studied period. The temporal trends of SO₄^2-, Na⁺ and TDS had either a negative significant trend or no trend in the Yazd area. Considering ranking maps, TDS, Cl^- and Mg²⁺ had high impacts on determining the GQI. These trends were positive in Yazd city and consequently the GQI maps could not confirm the negative temporal trend and zoning maps. This finding showed that the use of qualitative indicators could neutralize the effects of the parameters on each other and provide a better and acceptable result. In all, the transfer water with appropriate quality could control the increase of the TDS, SO₄^2-, Na and caused an increase in Cl^- in these areas. There are many effective factors to study water quality, so its description seems to be difficult. Therefore, using water quality indicators can provide total water quality conditions in a concise and understandable way.