Journal of Water and Soil Science

Investigating the Performance of SewerGEMS Software in Simulating Urban Runoff for Small Basins (Case Study: Minab City)

J. Abedi Koupai

Urban runoff is a serious issue due to urbanization and climate change. Therefore, paying attention to rainfall-runoff simulation models is important to manage and reduce adverse consequences. In this research, the performance of the SewerGEMS software was examined by studying different modes based on the number and area of sub-basins. Two modes, consisting of nine and seventeen sub-basins, were evaluated with varying durations of rainfall of 6 and 12 hours. Additionally, the performance of three methods for calculating concentration time (Kerpich, Brnsby-Williams, Carter) was compared to simulate flood hydrographs in Minab City. The results showed that the total volume of produced runoff in the nine sub-basins was 4% higher than in the seventeen sub-basins. The maximum runoff peak flow in the nine sub-basins was also 20% higher than in the seventeen sub-basins. Furthermore, the Brnsby-Williams method exhibited the least software continuity error among the three calculation methods for concentration time. On the other hand, the Carter method had the highest continuity error. The concentration time calculated by this method in some sub-basins exceeded the 6-hour duration of rain. A t-test was performed to compare the peak discharge data obtained from the Kerpich and Barnesby-Williams methods. The results indicated a significant difference between the data from the two methods at a 95% confidence level (p<0.05). Considering that the Kerpich method is suitable for calculating concentration time in small basins, it was used to compare the nine and seventeen sub-basins. Based on the findings, it was observed that merging the sub-basins and reducing their number from seventeen to nine resulted in an increase in the total volume of produced runoff from approximately 123,839 cubic meters to 128,446 cubic meters, as well as an increase in the maximum peak flow of runoff from about 2.400 m3/s to 2.884 m3/s. This demonstrates an increase in both the total volume and maximum peak discharge of the runoff.

The Effect of Temporal Distribution Pattern of Rainfall Intensity on Runoff and Soil Loss in a Hillslope in a Semi-Arid Region

A.R. Vaezi

The temporal distribution pattern of rainfall can play a role in the production of runoff and soil loss during rainfall. This study investigated four rainfall patterns: uniform, advanced, intermediate, and delayed rainfall under field conditions. The rainfall height in all rainfall patterns was 20 mm. In the uniform rainfall pattern, a constant rainfall intensity (40 mm h^-1) was used and in the non-uniform rainfall patterns, a maximum rainfall intensity of 40 mm h^-1 was applied for a 15-minute duration. The experiments were carried out in 60 cm × 80 cm plots on a hillslope with a slope gradient of 9% at three replications. Rainfall patterns were set up on the plots in five events with an interval of one week. The results showed a significant difference between rainfall patterns in runoff and soil loss (p<0.01). This difference was due to the destruction of surface soil structure and the reduction of water infiltration rate, especially during peak time of rainfall intensity (40 mm h^-1). The highest runoff occurred in the delayed rainfall (3.43 mm) while, the highest soil loss (61.47 g m^-2) was observed in the intermediate rainfall, which was associated with the peak intensity of rainfall at the end of the rainfall and its role in the destruction of the soil structure on the one hand, and the loss of infiltration rate on the other hand. Variation of runoff and soil loss from one event to another indicated that soil loss is in line with runoff production in uniform rainfall, while soil loss did not follow runoff in other rainfalls. Soil loss in these rainfalls was affected by both runoff production and availability of erodible soil particles. These results revealed the necessity of studying the rainfall intensity distribution pattern for accurate prediction of soil erosion and determining soil loss variation event by event in the semi-arid region.

Investigation of Potential and Performance of Five Chemical and Mineral Mulch in Stabilizing Sand Dunes

S.M. Abtahi

Today, wind erosion and dust are an environmental crisis, not just in desert areas but also in the entire country, and putting many costs. The combat against wind erosion in many desert areas by using oil mulches and the cultivation of compatible plants started in the 40s. However, the use of petroleum in addition to mulching the environmental problems, due to the high costs of purchase, displacement, and dispersion, is not economical. Therefore, the performance of non-oil and chemical mulch on dunes was investigated in Kashan. The research on fertilizer application of mulch under a completely randomized design includes: control (no mulch), a polymer mulch, potas, Fars, Paya, and Akrilik at 3 reps (3 sand hills) and the amount of erosion (with the help of the embedded indices in the hills), the survival of plants cultivated in the form of cuttings and seedlings, the percentage of humidity and temperature of each iteration were measured and variance analyses were performed. Field surveys and the results of the statistical analysis showed that the strength resistance of Fars, Paya, and Akrilik is almost the same. Observation of wood indices showed that Fars, Paya, and Akrilik mulches have almost the same strength in terms of wind resistance (almost no wind resistance). Fars mulch after 8 months of spraying showed small fractures due to the loss of flexibility. The study of soil temperature statistics showed that the treatments under mulch had no significant temperature difference compared to the control treatment. A comparison of soil moisture data indicated a high moisture percentage in the potash mulch treatment. The survival rate of cultivated plants was higher in Paya and Akrilik treatments. According to the results, Akrilik, Paya, and Fars mulch are recommended for sand fixation. One of the limitations of research in desert areas is the uncontrollability of environmental and human conditions. So, it is recommended to close the entire mulching area and use a mobile wind tunnel device at the project site to determine the wind slavery at different speeds.

Estimation of the SZIsnow Snow Index on Basin Scale Using the GLDAS Database

M.R. Sharifi

Drought monitoring in snowy basins requires modifications in common drought indices, called snow drought indices. The latest developed snow index is SZIsnow. The SZIsnow index calculating with special algorithm requires access to the values of 22 different climatic and physical variables, including soil moisture at a depth of 0 to 10 centimeters, soil moisture at a depth of 100 to 200 centimeters, air temperature, water equivalent to snow, runoff from snow melting, snowfall, rainfall, total precipitation rate, evaporation and transpiration, wind speed, surface runoff, groundwater runoff, potential evaporation, air pressure, relative humidity, net latent heat flux, ground heat flux, net sensible heat flux, evaporation from bare soil, evaporation from the canopy, and potential evapotranspiration. So far, the mentioned index has been calculated only on a continental scale. Drought monitoring at the basin scale is important as one of the management aspects of water resources. On the other hand, due to the lack of sufficient information to estimate the mentioned parameters, the use of information from global databases will be a solution. Therefore, in this research, while introducing the process of calculating the SZIsnow index, in the Dez catchment area, extracting the required parameters of the index in a time scale of 3, 6, and 12 months and a period of 41 years (1982 to 2023) using data GLDAS and then drought monitoring of the basin was studied. The results showed that the new SZIsnow index is a multi-variable index that provides the possibility of calculating the index due to the existence of parameters that lack ground observations and on the other hand, the availability of the reliable GLDAS database. Also, the results showed that in the time steps of 3, 6, and 12 months, July at -0.59, June at -0.45, and October at -0.35 had the highest amount of drought, respectively.

Investigating the Trend of Temperature Changes and Evaluating the Relationship Between Temperature with Yield and Biomass (Case Study: Forage Maize in Qazvin)

H. Ramezani Etedali

Climatic factors play an important role in the growth and development of plants and affect agriculture. The tolerance threshold of plants for each of these factors is limited. Any change in these factors can directly and indirectly have significant effects on agricultural production. Meanwhile, temperature stress is one of the most important damaging phenomena that causes many problems for production and yield. In this research, the time of occurrence of temperature stress with a statistical period of 44 years (1980-2023) and the relationship between air temperature with yield and biomass were investigated. According to meteorological data, June, July, and August were known as the hottest months of the year. On the other hand, the most heat waves were observed in July and August in the years 1997, 2014, and 2018, which led to a decrease in the quality of the product or the loss of the plant. According to the model evaluation results, the accuracy of the model in simulating days to flowering and days to maturity was confirmed using R² (0.8 and 0.51) and NRMSE (15.36 and 7.12). Also, the model was simulated for the studied fields with deviation percentages of 1.92, 5.65, 4.94, 1.58, 0.96, and 1.49%, respectively. It showed that the model had a satisfactory performance and could be used for maize production planning. Next, the relationship between temperature, yield, and biomass was investigated, and there was a negative and significant relationship between temperature, yield, and biomass at the 99% confidence level.

Assessment of Geostatistical Approach to Spatial Distribution of Soil Fertility Characteristics of the Southwest of Shiraz in Different Land Uses

H.R. Owliaie

The spatial distribution of soil characteristics is a fundamental factor for planning sustainable agriculture. Geostatistical methods are widely used to determine the spatial variability of soil characteristics in unknown locations. This research was carried out to evaluate the geostatistical methods for zoning some characteristics of the Darnagan area including agricultural (crop and horticultural) and pasture land uses in the southwest of Shiraz. 134 surface soil samples were collected with a grid pattern from three different land uses, and some of their fertility characteristics were measured. The results based on precision criteria revealed that exponential co-kriging was the best method for interpolating P, J-Bessel for K and Fe, stable model for Ca and Mn, tetra spherical model for N and Mg, Gaussian model for Zn, and rational quadratic model for Cu. The weak spatial structure was obtained for Zn, medium for N, K, and Mn, and strong for other variables. According to spatial distribution maps, 96, 28, and 24% of the studied area are deficient in nutrients N, P, and K, respectively. Concerning micronutrient elements, 78% and 63% of the region are deficient in Fe and Zn, respectively. The statistical comparison of the studied characteristics indicated a significant difference in P, K, Fe, Mn, Ca, Mg, and CEC amounts in different land uses.

Investigation of the Use of Irrigation with Drainage Water at Different Salinity and Water Stress Levels on Quinoa Yield and Yield Components (Case Study: Ahvaz Climatic Conditions)

S. Borumandnasab

Quinoa, a nutritionally rich crop with remarkable adaptability to unfavorable environments, exhibits a high tolerance to salinity. Reusing agricultural drainage water is a natural and important method in drainage management that increases farmers' income, sustainable production, and food security. The objective of this study was to investigate the effects of irrigation with agricultural drainage water, salinity stress, and water deficit on the yield and yield components of quinoa (Titicaca) under salinity levels of 2, 10, 15, and 20 dS/m and irrigation levels of full irrigation, 80%, and 60% of the crop water requirements. The experiment was conducted with three replications using a split-plot design with a randomized complete block design (RCBD) at the experimental farm of the Faculty of Water and Environmental Engineering at Shahid Chamran University of Ahvaz, during the fall and spring seasons of the years 2022 and 2023. The water requirement of Qinoa was determined gravimetrically by measuring soil moisture before each irrigation and increasing it to field capacity. The experimental treatments were imposed after seed germination and from the start of cultivation. The plants were harvested and transported to the laboratory for drying and yield component analysis upon physiological maturity. The results revealed that salinity stress had a more pronounced impact on reducing quinoa yield and yield components compared to water stress. The highest and lowest grain yields were observed in the autumn season, reaching 5.45 and 1.8 t/ha under the treatments of S1I1 and S4I3, respectively. Similarly, in the spring season, the highest and lowest grain yields were 3.87 and 0.73 t/ha under the same treatments, respectively.

Investigating the Energy Loss in the Dentated Flip Bucket and Dentated Triangular Sill Spillways in Laboratory and Numerical Conditions

A.R. Masjedi

The application of flip bucket and triangular launchers with different shapes has been given more attention due to safety and better energy consumption to protect the downstream bed of water structures, as well as economic benefits compared to other energy consumers. The objective of this research was to investigate the energy loss of the passing flow in the dentated flip bucket and dentated triangular sill spillways in laboratory and numerical conditions. Physical and numerical modeling was used in a rectangular flume with a length of 9 meters, a width of 0.5 meters, and a height of 0.5 meters, flip bucket, and triangular spillways with dentated with specific dimensions according to the USBR standard in different discharges intensities in laboratory and numerical conditions. The amount of energy loss in the dentated flip bucket spillway was 71.4% and the dentated triangular sill spillway was 74.8% in laboratory conditions, which showed that the dentated triangular sill spillway has a better performance in terms of energy loss than the flip bucket and triangular spillway. The results showed that the shape of the spillway geometry and the presence of the dentated at the end of the structure is an important and influential factor in the amount of energy loss of the currents passing through the dentated flip bucket and dentated triangular sill spillways, which causes more broken and compressed flow lines and, as a result, an increase in speed at the moment. The launch and finally the relative loss of energy is more downstream of the structure. After determining the better performance of the dentated triangular sill spillway in energy loss, the numerical simulation of the dentated triangular sill spillway was performed using the numerical calculation method in Flow-3D software. The results of the analyses indicated that the amount of energy loss in the dentated triangular sill spillway in the numerical calculations was 87.5%, which showed the alignment and correctness of the tests performed with the laboratory conditions.

Hydrological Simulation of Mountainous Areas Using SWAT Model

S. Eslamian

This study aims to investigate the possibility of hydrological simulation of the Azna-Aligoudarz area, which is located in the upper reaches of Karoun Bozorg basin and in the east of Lorestan province. To carry out this research, the daily meteorological data related to the Aligoudarz synoptic station and the rainfall of Kamandan and Dareh Takht rain gauge stations in the period of 1991-2023, the observational discharge related to the Marbareh hydrometric station in the period of 1991-2021, soil map, land use and digital elevation map of Azna-Aligoudarz basin was used. The period of 1991 and 1992 was considered for warm up the model, the validation period from 1993 to 2016, and the validation period from 2017 to 2021. Based on the simulation done in this area, the model had weakness in simulation. After the initial simulation, the model was calibrated. After analyzing the sensitivity of different parameters, 22 effective parameters were selected and the model was calibrated. The evaluation results showed that the NSE value of 0.60 and 0.56 and the R² coefficient value of 0.61 and 0.78 respectively were obtained for the calibration and validation stages. Based on the coefficients obtained in both calibration and validation stages, it was found that the model had a satisfactory accuracy in the hydrological simulation of Azna-Aligoudarz area.

Simulation of Scouring Behind Coastal Walls by Lagrangian Method Using the 𝜇 (I) Rheology Model

A. Shirzadi

The rapid and complex movement of sediments in rivers and coastal areas with highly erosive and unsteady flows presents river engineers with numerous problems in the geomorphology of alluvial rivers. Accurately predicting these complex processes in the water-sediment system (a multiphase, dense, granular flow system) is still a major challenge for mesh-based models. Due to the ability of meshless Lagrangian methods to model large deformations and discontinuities, meshless Lagrangian methods can provide a unique way to deal with this complexity. In the current research, the capabilities of the weakly compressibility moving particle semi-implicit (WC-MPS) model in soil-fluid interaction modeling are developed to enable the modeling of sediment transport and erosion effects behind coastal walls. In this method, granular material is considered a non-Newtonian and viscoplastic fluid. The 𝜇(I) rheological model has been used to predict the non-Newtonian behavior of the granular phase. To verify the application of the present model in simulating the interaction of liquid and solid phases, first, the widely used problem of dam break on an erodible bed was modeled. The NRMSE model was calculated to be approximately 6%, which indicates the efficiency and accuracy of the target model in this problem. At the end, the scouring of coastal walls was simulated by the WC-MPS method using 𝜇(I) rheology model. Investigations show that the processes related to erosion and scouring can be well modeled using the current Lagrangian method. The numerical results show excellent agreement with the laboratory measurements. It should be noted that the mean error of the mentioned model is estimated to be 10%.

Classification of Rangeland Bioclimatic Areas of Iran Based on Spectral Analysis

R. Modarres

This study was conducted to present rangeland bioclimatic zoning for Iran based on the changes in the power spectrum of the average monthly Net Primary Production (NPP) of the rangelands of Iran. Fluctuations of the mean monthly power spectrum of the NPP signal of rangelands of Iran from 2000 to 2022 were analyzed using the Power Spectrum Density (PSD) method in the frequency band between 0-100 Hz. In 24 bioclimatic subzones, there are four common periods in all sites at frequencies of 0 (no change is repeated), 8.34 (3.59 days), 16.66 (1.80 days), and 25 (1.2 days) Hz observed, which shows that the major data changes occur in those periods and that the NPP changes of Iranian rangeland are more influenced by global and regional effects than local effects. The maximum power of these spectra is concentrated in high time scales. Therefore, cycles with lower frequency (higher time scale) are more important than cycles with higher frequency (shorter time scale) and show that the changes of NPP in Iranian rangelands have long-duration cycles under climate fluctuations. In the present research, Iran was classified into 5+1 rangeland bioclimatic zones using the results of the monthly mean power spectrum of the NPP signal of rangelands, the Wards clustering method, and the Euclidean square distance. It seems that this method provides a proper match between biological boundaries and climate. Pearson correlation coefficient was used to investigate the coherence of rangeland bioclimatic regions within each homogeneous group. Correlation results showed a significant spectral density similarity within groups at the significance level of 0.01% between rangeland bioclimatic regions, especially in the second and fifth clusters.

Analysis of Seepage Flow and Hydraulic Gradient in the Body and Foundation of Alavian Earth Dam

M. Kouhdaragh

Dams, as man-made artificial structures, play a significant role in providing water in various sectors, including agriculture, industry, electricity generation, and flood control. Various soil compounds such as sand, clay, and stone are used for the construction and establishment of earth dams. In this research entitled "Investigation and analysis of Seepage flow and hydraulic gradient in the body and foundation of Alaviyan earth dam using SEEP/W software", the effects of Seepage flow and hydraulic gradient in the body and foundation are investigated. This research analyzes the details of this process using SEEP/W software and analyzes the obtained results. Theoretical foundations related to Seepage flow and hydraulic gradient in earth dams and their importance in the stability of dams are discussed as one of the most important issues of civil engineering. Methods of controlling water seepage from earth dams include the use of seals, walls made with grout mortar, impermeable cores, metal shielding, and impermeable blankets upstream of the dam. In this study, drains, seals, and clay blankets are used as water seepage control methods. The results show that the use of a watertight wall reduces the amount of Seepage because this wall prevents water from flowing through the body of the dam. In general, this research ends by providing quantitative results and recommendations to improve the stability of dams and reduce the possibility of risks caused by seepage flow and hydraulic gradient, and the important elements that should be considered in the design and construction of earth dams. Reviews. In this study, the effects and performance of earth dams have been investigated using finite element methods, and the performance of dams has been evaluated. GEOSTUDIO finite element software was used for modeling. The results of modeling include the investigation of parameters such as phreatic lines, the effect of the water level behind the dam, the clay blanket, and the water seal. Also, the leakage rate from the dam has been extracted and analyzed for different states defined in the model.