Showing 234 results for Model
M.j. Zareian, R. Seraj Ebrahimi, H. Dehban,
Volume 28, Issue 3 (10-2024)
Abstract
In the present study, the impact of climate change on maximum temperature and daily precipitation in 16 weather stations was investigated in the Sefidrood Basin from 2023 to 2052. 10 AOGCM models related to the sixth IPCC Assessment Report (CMIP6) were ranked based on their ability to simulate temperature and precipitation in the historical period (1980 to 2014). Then, the maximum temperature and daily precipitation outputs of the best model at each weather station were extracted using the LARS-WG downscaling model under three emission scenarios SSP126, SSP245, and SSP585 from 2023 to 2052. The Mann-Kendall test (95% confidence level) was also used to investigate the trend of changes in the average maximum temperature and maximum daily precipitation. The results showed that different AOGCMs have different accuracies in simulating temperature and precipitation in different regions of the basin, and their accuracies in simulating temperature were better than simulating precipitation. In general, the IPSL-CM6A-LR and HadGEM3-GC31-LL models had the best performance in simulating maximum temperature and precipitation, respectively. Results also indicated that the mean maximum temperature will increase between 0.9 and 2.8 °C in different emission scenarios. Also, the mean maximum daily precipitation will change between -8.6 and 7.17 mm in different emission scenarios.
M. Amiri, E. Fazel Najafabadi, M. Shayannejad,
Volume 28, Issue 3 (10-2024)
Abstract
Piano key weirs are a type of non-linear weir that have a higher discharge coefficient than similar linear weirs. These hydraulic structures have a lightweight foundation and a simple structure is designed and installed on dams and drainage channels. Due to the high efficiency of these weirs, the investigation of downstream scour and ways to reduce it has been the focus of engineers in recent years. In the present study, a trapezoidal type C piano key weir, three discharges, and three tailwater depths were used. Two obstacles with heights of 0.02 and 0.04 meters were also used at the end of the weir exit keys. The results showed that the presence of an obstacle reduces scour at the toe of the weir. The amount of reduction in scour at the toe of the weir was greater in the weir with a larger obstacle height than in the weir with a smaller obstacle height, and in both cases was less than in the simple weir. The presence of an obstacle reduces the maximum depth of scour and moves the distance of the maximum depth of scour away from the toe of the weir. In the weir with obstacle heights of 0.02 and 0.04 meters, compared to the weir without an obstacle, the amount of maximum scour depth is approximately 16.4% and 26.9% less, and the distance of the maximum scour depth is approximately 8.7% and 19.1% more than the weir without an obstacle. The scour index in weirs with obstacles is less than in weirs without obstacles, which can reduce the risk of weir overturning. The lowest value of the scour index was observed in the weir with an obstacle height of 0.04 meters, which is approximately 41.2% less than the weir without an obstacle.
M.a. Abdollahi, J. Abedi Koupai, M.m Matinzadeh,
Volume 28, Issue 3 (10-2024)
Abstract
Today, the problems related to floods and inundation have increased, particularly in urban areas due to climate change, global warming, and the change in precipitation from snow to rain. Therefore, there has also been an increasing focus on rainfall-runoff simulation models to manage, reduce, and solve these problems. This research utilized SewerGEMS software to explore different scenarios to evaluate the model's performance based on the number of sub-basins (2 and 8) and return periods (2 and 5 years). Additionally, four methods of calculating concentration time (SCSlag, Kirpich, Bransby Williams, and Carter) were compared to simulate flood hydrographs in Shahrekord city. The results indicated that increasing the return period from 2 to 5 years leads to an increase in peak discharge in all scenarios. Furthermore, based on the calculated continuity error, the Kirpich method is preferred to estimate the concentration-time in scenarios with more sub-basins and smaller areas. For the 2-year return period, a continuity error of 4% was calculated for the scenario with 2 sub-basins, while for the 5-year return period, the continuity error was 19%. On the other hand, the SCSlag method is preferred to estimate the concentration-time in scenarios with fewer sub-basins and larger areas. For the scenario with 8 sub-basins, a continuity error of 16% was calculated for the 2-year return period, and 11% for the 5-year return period.
M. Neisi, M. Sajadi, M. Shafai Bejestan, J. Ahadiyan,
Volume 28, Issue 3 (10-2024)
Abstract
Side weirs are hydraulic structures employed in irrigation and drainage channels as diversion devices or head regulators. The increasing efficiency of the structure of side weirs for constant head has been one of the concerns of researchers in the last decade. The use of different forms of sharp crest, labyrinth, piano key, and increasing the length of the overflow by changing the geometry of the crest have been investigated. In this research, a new type of triangular-shaped side weir has been studied in the laboratory under different hydraulic conditions in sub-critical flow conditions. The results demonstrated that by inclining the crests of the triangular side weir, the amount of vortex created at the entrance of the opening was reduced. So the discharge coefficient and the flow volume over the side weir showed an increase of up to 27% and 48%, respectively, compared to the normal triangular and rectangular side weirs. Also, after analyzing the data, a non-linear equation was presented to estimate the discharge coefficient with the dimensionless parameters of the ratio of the upstream depth to the weir height (y1/p) and the upstream Froud number (Fr1) with an accuracy of ±15% and NRMSE=0.134.
M. Tajsaeid, M. Gheysari, E. Fazel Najafabadi, R. Jafari, E. Seyfipurnaghneh,
Volume 28, Issue 3 (10-2024)
Abstract
Soil moisture is one of the important and determining factors for plant growth, the rate of evaporation and transpiration, and water management in the field. Therefore, its measurement has special importance. The surface soil has a great diversity in soil moisture and different methods were used to measure this property. Due to the problems of contact methods of soil moisture measurement, remote sensing has gained attention because of the possibility of analyzing and monitoring soil moisture on a large and global scale. In this research, satellite data and moisture measured in selected fields located in Hormoaz Abad Plain have been analyzed and compared. Sentinel-2 satellite data have been analyzed using the Google Earth Engine system. The results of this research showed that the use of triple indices in the OPTRAM model to estimate moisture is not very accurate, but the use of the EVI plant index has provided better results than the other two indices.
M. Ranjbari Hajiabadi, J. Abedi Koupai, M.m. Matinzadeh,
Volume 28, Issue 4 (12-2024)
Abstract
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.
F. Safari, H. Ramezani Etedali, A. Kaviani, L. Khosravi,
Volume 28, Issue 4 (12-2024)
Abstract
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.
H.r. Owliaie, A.r. Salehi, Gh.r. Zareian,
Volume 28, Issue 4 (12-2024)
Abstract
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.
R. Daneshfaraz, M. Majedi Asl, T. Omidpour Alavian,
Volume 29, Issue 1 (4-2025)
Abstract
Weirs play a crucial role in flood management and dam safety, accounting for a significant portion of the construction costs of dams. The selection of floods with long return periods for flood design is of utmost importance. However, in some cases, increasing the weir capacity by widening it may be impossible due to topographical limitations. One solution to enhance the flow capacity of weirs is the application of labyrinth weirs. These weirs increase the effective length of the weir crest within a given width, allowing for the passage of higher flow rates while maintaining similar hydraulic conditions. In this study, the hydraulic performance of labyrinth weirs is investigated using the Flow3D numerical model and laboratory data. Since laboratory experiments are time-consuming and costly, employing numerical simulations to achieve more accurate and reliable results for evaluating the hydraulic behavior of labyrinth weirs is prioritized. The results of the simulations indicate that the Flow3D software, utilizing statistical parameters such as R², DC, and RMSE, achieves values of (0.9805, 0.9725, and 0.0142), respectively. This demonstrates its capability to model the flow passing through weirs with high accuracy. The obtained values of the discharge coefficient in Flow3D show a high agreement with the laboratory data from Crookston. The approximate alignment of these results indicates the high accuracy of the numerical model. Additionally, in comparison to different discharges, the relative computational error observed for flow rates of 0.35, 0.6, and 0.44 (cubic meters per second) was approximately 0.5 percent, while for flow rates of 0.3, 0.4, and 0.57, the corresponding errors were 8, 6, and 4 percent, respectively. The results indicate that these tools can be effectively utilized in precise hydraulic analyses and the optimization of weir designs, irrigation systems, and fluid dynamics phenomena.
M. Zarinibahador,
Volume 29, Issue 1 (4-2025)
Abstract
The calcium carbonate equivalent (CCE) in soil is one of the most important soil properties. Predicting the amount of calcium carbonate equivalent in soil is essential for sustainable soil fertility management. The present study aimed to digitally map calcium carbonate equivalent using auxiliary environmental variables, Landsat 8 satellite images, and predictive models and to present the best models in the Badr watershed in the south of Qorveh district. In the first phase, a geomorphologic map was created using a geologic map and based on the ZINC method in a geographic information system environment. In the second phase, the location of 125 survey profiles was determined using the Latin hypercube technique, and the calcium carbonate equivalent of the soil horizons was measured by acid titration. The auxiliary variables included derivatives of the digital elevation model, remote sensing indices from the Landsat 8 satellite, and a geopedological map. The principal component analysis (PCA) method was used to select suitable auxiliary variables. In the third phase, the modeling was carried out, digital maps of the soil classes and properties were created, and the models were evaluated. Two different cases were investigated in this study to estimate the calcium carbonate equivalent of the soil. In the first case, artificial neural network models, decision tree analysis, random forest, and the K-nearest neighbor model were used for prediction. The multiple linear regression model was also used to combine the results of the models. Among the models used to predict the equivalent amount of calcium carbonate using the 10-fold cross-validation method, the multiple linear regression (MLR) model had the highest prediction accuracy with a coefficient of determination of 0.796 and a mean square error of 6.514. In the 5-fold cross-validation method, the K-nearest neighbor (KNN) model had the highest predictive accuracy with a coefficient of determination of 0.9845 and a root mean square error of 2.1258. Due to the spatial nature of the 10-fold cross-validation method, the use of this method is preferable to the 5-fold cross-validation method. In addition, the most important auxiliary variables in order of importance to predict the calcium carbonate equivalent in soil were the carbonate index, slope direction, geomorphology, the base level of the catchment network, and the slope of the catchment.
F. Zolfaghari, S. Eslamian, A.r. Gohari, M.m. Matinzadeh, S. Azadi,
Volume 29, Issue 2 (7-2025)
Abstract
Drought represents one of the most critical natural disasters, exerting profound impacts on agriculture, society, the economy, and water resources. Various indices are used to monitor drought and its effects. This study aims to monitor drought in the Zayandeh-Rud Basin using the Standardized Precipitation Index (SPI), the Standardized Precipitation-Evapotranspiration Index (SPEI), the Evaporative Demand Drought Index (EDDI), the Palmer Drought Severity Index (PDSI), and the Reconnaissance Drought Index (RDI). All these indices are based on potential evapotranspiration, incorporating parameters such as precipitation, temperature, relative humidity, wind speed, and sunshine duration. These five indices were calculated and evaluated during the statistical period of 1993–2023 for meteorological stations in Isfahan, East Isfahan, Kabootarabad, Daran, Shahreza, Najafabad, and Mobarakeh. After calculating the indices and using spatial zoning maps, the studied stations were compared in terms of these indices. The continuity of dry and wet periods, as well as the intensity of droughts and wet spells, was analyzed. Subsequently, drought intensities during different years in these stations were ranked using the TOPSIS model based on factors such as precipitation, potential evapotranspiration, and station elevation. The results showed that in stations with a dry climate (such as Isfahan, East Isfahan, and Shahreza), drought occurrences (as indicated by higher rankings) have been consecutive over multiple years. Comparing the performance of the indices in the studied stations using spatial zoning maps revealed that the intensity of droughts and wet spells in regions with dry and semi-dry climates was not very significant. However, in areas with humid climates, the fluctuations in drought and wet spell intensities were quite substantial. The findings indicate that the PDSI and EDDI indices are more suitable for evaluating drought in dry climates.
A. Akbarian Khalilabad, H. Karami, S. F. Mousavi,
Volume 29, Issue 3 (10-2025)
Abstract
The reduction of soil permeability due to the sedimentation of suspended particles is a significant challenge to the efficient operation of artificial recharge systems. In this study, the effects of sediment concentration (0.5, 2, and 4 g/L), soil particle size, and vertical distribution on clogging processes were investigated using laboratory soil column experiments. The results showed a two-phase decrease in permeability: a rapid initial drop caused by the blockage of coarse pores during the first 10 minutes, followed by a second phase where the system reached a relative equilibrium. Higher sediment concentrations led to a faster decline and lower equilibrium values of permeability. Fine-grained soils, despite having lower initial permeability, demonstrated greater resistance to clogging, while coarse-grained soils experienced more severe reductions. Vertical analysis indicated that the most significant permeability loss occurred at a depth of 40-50 cm, while deeper layers showed increased permeability due to the limited penetration of suspended particles. These findings can inform the selection of appropriate materials, the design of subsurface layers in recharge basins, the prediction of system lifespan, and the regulation of sediment load in inflows to enhance the efficiency and sustainability of artificial recharge systems.
M. Golestani, S. F. Mousavi, H. Karami,
Volume 29, Issue 3 (10-2025)
Abstract
Groundwater is a vital resource for meeting drinking, agricultural, and industrial needs in arid and semi-arid regions of Iran. In this study, quantitative and qualitative changes in groundwater in the Garmsar Plain were modeled using GIS, MODFLOW, and MT3DMS software during the period 2011-2013. Spatial and climatic data were comprehensively processed and prepared in the GIS environment, and groundwater flow was simulated using the MODFLOW model, and water quality changes were analyzed using the MT3DMS model. After validation with field data from 2012 to 2013, the model showed acceptable accuracy with statistical indicators of mean absolute error (MAE) in the range of 0.4 to 0.5 meters and root mean square error (RMSE) between 0.5 and 0.6 meters. The modeling results showed that a 15% increase in water withdrawal led to a decrease in the water table of up to 8 meters, a constant withdrawal led to a decrease of 7 meters, and a 15% decrease in withdrawal led to a decrease of 5 meters in the water table. From a quality perspective, the decrease in withdrawal improved the quality of irrigation water but increased the concentration of some pollutants, which requires the development of effective management strategies to protect groundwater resources. The findings of this study illustrate the importance of sustainable exploitation and smart management of groundwater resources in the Garmsar Plain.
M. Shayannejad, E. Fazel Najafabadi, F. Hatamian Jazi,
Volume 29, Issue 3 (10-2025)
Abstract
Regarding the increasing need for water resources and the decline of surface water resources, awareness of these resources is a crucial need in planning, developing, and protecting them. This research was conducted to model the water quality index (the most widely used feature of determining water quality) using machine learning models (Random Forest and Support Vector Machine) in the Zayandehrood River. Regarding the large number of water quality indices, the NSFWQI index was used in this study. First, this index was calculated, and then, input data, including water quality characteristics of 8 stations over 31 years, and the river water quality index were used. In this research, 80% of the data was used in the training stage, and the remaining 20% was used in the evaluation stage. The optimal model was selected based on the evaluation criteria, including R2, CRM, and NRMSE. The results showed that the Support Vector Machine algorithm (0.931 < R² < 0.982, 1.321
