Showing 411 results for Water
F. Afsharipour, M.r. Sharifi, A. Motamedi,
Volume 28, Issue 4 (12-2024)
Abstract
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.
S. Zandi, S. Borumandnasab, M. Golabi,
Volume 28, Issue 4 (12-2024)
Abstract
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.
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.
S. Ashkevari, S. Janatrostami, A. Ashrafzadeh,
Volume 29, Issue 1 (4-2025)
Abstract
In this study, a conceptual model based on dynamic systems was developed to optimize the management of water, land, and agricultural production (tea and rice) in the irrigation zones of the Sefidroud irrigation and drainage network. To understand the behavior of the network and create a simulation model of the system, a dynamic systems modeling approach was employed, and the simulation was conducted using MATLAB/Simulink. Subsequently, the optimization model of the studied system was developed as a multi-objective model using a genetic algorithm. Various management scenarios were implemented through the weighting of the objective functions. The results showed that selecting the best response from multi-objective optimization models depends on the weighted values of the objective functions, and by changing these values, decision-makers can provide various responses to complex optimization problems. The optimization model determines the cultivated area and water allocation in such a way as to minimize water scarcity and maximize crop performance through different weighting combinations. Furthermore, the findings indicate that the canals of the irrigation network play a crucial role in meeting water needs, and equitable water allocation is essential to prevent excessive extraction and negative consequences, such as saline intrusion and land subsidence. The study demonstrates that the best solutions are contingent upon local conditions and decision-makers' policies. To achieve maximum economic benefits and address water needs, it is suggested to use a weighting combination close to (w1=1,w2=2). Ultimately, this model assists managers and decision-makers in minimizing water scarcity in the region by adjusting cropping levels and optimizing the use of available water resources.
J. Karimi Shiasi, F. Fotouhi Firoozabad, A. Fathzadeh, M. Hayatzadeh, M. Shirmardi,
Volume 29, Issue 1 (4-2025)
Abstract
One of the main factors contributing to water erosion is the inherent characteristic of soil erodibility. Erodibility depends on particle size distribution, organic matter, structure, and soil permeability. This research aimed to investigate changes in the soil erodibility factor across geomorphological facies. The soil erodibility index was estimated by sampling 58 points within the geomorphological facies of the Dorahan watershed, using the Wischmeyer and Smith method. In the laboratory, soil granularity distribution, organic matter, soil structure, the amount of gravel, lime, salinity, acidity, and sodium absorption ratio were measured. Results indicated that soil erodibility across the entire area ranges from 0.0148 to 0.0661 (t.hr/Mj.mm). The soil erodibility index (K) for the hro-p1 and hro-p2 facies is higher than for others and exhibits the widest range of variations compared to the other facies. The lowest range of changes within geomorphological facies is associated with the hrc facies. The erodibility index decreases from the east to the west of the basin due to the presence of exposed rock faces, which protect the soil as a cover layer.
A. Mirzaei, A. Soltani, F. Abbasi, E. Zeinali, Sh. Mirkarimi,
Volume 29, Issue 1 (4-2025)
Abstract
Water scarcity and adaptation to it are the most significant issues facing Iran's agriculture. Optimizing the cropping pattern is one of the fundamental strategies for addressing water scarcity. This study evaluated the optimization of the cropping pattern in the irrigated lands of Fars province, one of Iran's key agricultural production areas. Linear mathematical programming and the SAWA system (System for Provincial Agricultural Water Balance and Accounting) were employed. The optimal cropping pattern (OCP) was designed to minimize applied irrigation water and was compared with the current cropping pattern (CCP) as well as a proposed cropping pattern from the Agricultural Jahad Organization (CPAJO) for the province for the cropping year 2023-2024. The results indicated that in the OCP, compared to the CCP, the cultivated area for the following crops decreased: wheat by 30%, barley, grain maize, silage maize, alfalfa, sugar beet, potato, cold- season legumes, and cold-season oil crops by 60%, rice by 80%, warm-season fruit trees by 42%, and vegetables by 13%. Conversely, the cultivated area for warm-season legumes and cold-season fruit trees each increased by 60%, while cold-season legumes increased by 150%. To meet the adaptation goals for water scarcity and sustainable agriculture outlined in this study, a 24% reduction in the irrigated cultivation area of the province was deemed necessary. The OCP achieved a 34% reduction in applied irrigation water at the provincial level without decreasing farmers' income. Compared to the CCP, the OCP led to a 32% reduction in the amount of plant production (by weight) at the provincial level. However, prioritizing plants with higher gross economic profit and lower water consumption over those with lower gross economic profit and higher consumption resulted in the gross economic return of the OCP being comparable to that of the CCP and the CPAJO. The comparison of OCP with CPAJO indicated that the CPAJO has not seriously considered adaptability to water scarcity or agricultural sustainability. The CPAJO needs to be reviewed and optimized to address water scarcity and ensure production stability in light of the impacts of excessive water withdrawal in the province.
B. Naderi-Samani, M. Ghobadinia1, B. Haghighati, S.m.r. Hosseini-Vardanjani, A.r. Ahmadpour-Samani,
Volume 29, Issue 1 (4-2025)
Abstract
Awareness of the impact of water deficit stress on the quantitative and qualitative performance of agricultural products, considering the recent recurrent droughts and reduced precipitation, is essential for water consumption management. This study aimed to evaluate the effects of different irrigation deficit treatments on the yield, yield components, and water use efficiency of autumn wheat in the Shahrekord region. An experiment with three replications was conducted in a completely randomized block design at the Agricultural and Natural Resources Research Center of Chaharmahal Va Bakhtiari Province during 2023-2024. The experimental treatments included four irrigation levels: full irrigation (T100), 80% of full irrigation (T80), 60% of full irrigation (T60), and 40% of full irrigation (T40). The application of the T60 deficit irrigation treatment resulted in a reduction of more than 14% in grain yield, while the T80 treatment caused a more than 31% decrease in grain yield. Additionally, the T60 treatment exhibited the highest water use efficiency at 1.22 kg per cubic meter, while the water use efficiency for the T100, T80, and T40 treatments was 1.06, 1.12, and 1.19 kg per cubic meter, respectively. The results showed that water deficit irrigation significantly affected the grain yield, biomass, and water use efficiency of autumn wheat under the climatic conditions of the Shahrekord region. The results of this study indicated that the T80 deficit irrigation treatment could have a more acceptable performance in terms of water efficiency.
I. Saleh, S. Zandifar, M. Khazaei,
Volume 29, Issue 2 (7-2025)
Abstract
Groundwater resources are affected by long-term drought conditions and have received less attention than other issues. The current research was carried out to investigate and zone the quantitative fluctuations of groundwater as well as the temporal analysis of groundwater drought using GRI in the study area of Shiraz in the Maharloo-Bakhtegan watershed. The zoning of groundwater table variations was done in the ArcGIS environment, and a representative hydrograph of the aquifer was prepared using 15-year data (2003-2018) of groundwater resources divided into three five-year periods. Also, the drought of the groundwater resources of the studied plain was investigated using the GRI index. According to the results, the highest level of the groundwater table is related to the northwestern area of the plain by 1810.1 m in October 2007, and the lowest water table was observed in the southern study area with the amount of 1423.6 m in October 2017. Also, the results showed that the groundwater table faced a drop of 6 m and an average annual drop of 0.5 m during the studied 15 years. The volume changes of the reservoir also indicated that, in addition to consuming the entire renewable reserve, a large part of the fixed reserve has also been exploited in the past years. The descending trend of GRI and its intensification in the last years of the studied period is one of the most important results of this research, which occurred due to population growth and increasing cultivated area, a decrease in precipitation, and climate change.
M. Khoshoei,
Volume 29, Issue 2 (7-2025)
Abstract
The issue of water scarcity or the limited availability of water resources, including concepts such as water stress, water shortage, and water crisis, is investigated in this study. Water stress refers to problems related to access to freshwater resources, particularly due to the excessive withdrawal of surface and groundwater. A water crisis describes a situation where the available clean and safe drinking water in a specific region is insufficient to meet demand. Factors like drought, reduced rainfall, and pollution can exacerbate water stress. Water shortage arises from reasons such as the inability to meet demand, economic competition over water quality and quantity, conflicts among users, the irreversible depletion of groundwater resources, and negative environmental impacts. This study provides an index to assess water stress for spatial analysis in the study area and analyzes relevant data by collecting information from various sources. This index utilizes both static and dynamic parameters to estimate drought and better depict water stress conditions. Static parameters include land use, slope, and soil type. Dynamic parameters include precipitation, temperature, and groundwater level. Kashan County was selected as the case study due to the continuous reduction in water resources. The results showed that in the water years 2005, 2014, 2020, and 2021, Kashan experienced the highest level of water stress, while in the water years 2002, 2004, 2010, 2012, 2013, and 2015, it experienced the lowest level of water stress.
M. Askari Jabarabadi, N. Mirghaffari, J. Abedi Koopaei,
Volume 29, Issue 2 (7-2025)
Abstract
The water footprint is an analytical tool that offers a better and more comprehensive view of how consumers or producers engage with freshwater consumption. Given the water crisis in the country, particularly in Isfahan Province, this study aims to estimate and compare the direct and indirect water footprints of several large industries, including Mobarakeh Steel, Iron Smelting, Refinery, and Power Plant, located in the Zayandeh River Basin. After identifying the desired objectives and study areas, as well as confirming the availability of the required data, information was gathered from the selected industries. Two methods were then utilized to aggregate the entire chain and the sum of steps to calculate the water footprint in the researched industries. According to the calculations, the direct and indirect water footprint in the iron smelting industry amounts to 196.9 cubic meters per ton of steel annually, of which 4.026 cubic meters is attributed to direct consumption and 17.5 cubic meters to indirect consumption. In a refinery, 18.80 liters of water are consumed directly and indirectly to produce one barrel of product (gasoline or diesel). Additionally, the direct and indirect water footprint of the Islamabad power plant is 1,198,320 cubic meters per terajoule, equating to 4.31 liters per kilowatt hour. The results of this study indicate that the indirect water footprint in the analyzed industries is equal to or exceeds direct water consumption, with both being equally significant. Finally, it is important to note that the results of this study can support decision-makers and policymakers in the industry, including those in the iron and steel, refinery, and power plant sectors, in managing their water footprint.
M. Asadi, M. Noshadi, A.r. Noshadi,
Volume 29, Issue 2 (7-2025)
Abstract
In this research, drinking water quality was investigated using acceptability, health, and nutrition-based indicators from 2010 to 2022 in Shiraz City (Fars province). Magnesium, fluoride, and calcium play a significant role in the contribution of drinking water in Shiraz City to the intake of dietary minerals. The acceptability water quality index (AWQI), health-based water quality index (HWQI), and drinking water quality index (DWQI) rankings in Shiraz City are excellent, but the average drinking water nutritional quality index (DWNQI) of Shiraz City is 77.52 ± 5.47, which falls within the good ranking. Therefore, while the conventional water quality indices (AWQI, HWQI, and DWQI) are excellent, the DWNQI index does not achieve an excellent rating, due to the inclusion of the nutritional value of water in the DWNQI index. In general, the trend of AWQI, HWQI, DWQI, and DWNQI over thirteen years in Shiraz City shows that the conventional drinking water quality indices (AWQI, HWQI, and DWQI) do not provide an accurate picture of the assessment of drinking water quality in many cases, as they do not consider the nutritional role of water. For this reason, water is sometimes treated more than necessary. Therefore, it is essential to revise the interpretation of drinking water quality using the DWNQI index to gain a comprehensive picture of drinking water quality.
S. Rezaei, M. Heidarpour, A. Aghakhani,
Volume 29, Issue 2 (7-2025)
Abstract
The growing concern for environmental protection and increasing demand for green approaches to address environmental problems have prompted researchers to explore a sustainable and reliable method for treating dyeing wastewater. One of the sustainable and reliable methods is the electrocoagulation process. In this study, a batch electrocoagulation reactor was designed to evaluate the efficiency of this process in treating dyeing wastewater. The effects of two parameters, electrode distance and retention time, on pollutant removal efficiency were investigated. Electrode distances of 2, 5, and 7 cm were tested, and retention times of 10, 15, 20, 25, and 30 minutes were examined. Results indicated that the optimal electrode distance was 5 cm and the optimal retention time was 20 minutes. Under these conditions, the removal efficiency of BOD, COD, TSS, color, and turbidity reached 83%, 85%, 98%, 98%, and 93%, respectively. The results of this research demonstrate the significant potential of the electrocoagulation system for treating dyeing wastewater.
M.r. Shoaibi Nobariyan, M.h. Mohammadi,
Volume 29, Issue 2 (7-2025)
Abstract
The objective of this study is to investigate the effects of solutes and water quality on evaporation amount and rate in two sandy and clayey soils. Soil samples containing aggregates and sand particles with diameters ranging from 0.5 to 1 millimeter were collected. Six columns were prepared during the experiment; three columns were filled with sandy soil and three with aggregated soil, each measuring 60 cm in height and 15.5 cm in inner diameter. One reference column was filled with distilled water. A saturated calcium sulfate solution was added to two columns, a 0.01 molar calcium chloride solution was added to two other columns, and distilled water was added to the remaining two. The amount of water lost through evaporation was recorded every 8 to 12 hours by weighing the columns. After approximately 130 days, the columns were sectioned, allowing for the establishment of moisture and solute concentration profiles for each soil column. The results indicated that the first and second stages of evaporation were distinguishable in sandy soil, whereas in clayey soil (aggregated soil), only the first stage of evaporation occurred due to the gradual transfer of water and the continuous hydraulic connection from the surface to the water table. The presence and type of solutes affected the evaporation rate and moisture profile, reducing evaporation and increasing water retention in deeper soil layers. Hydraulic connectivity (calcium sulfate > calcium chloride > distilled water) and the resulting capillary rise of and supply of evaporated water from higher layers caused a greater evaporation rate in the calcium sulfate compared to the calcium chloride and distilled water treatments in both soil types. Additionally, the formation of a salt crust on the soil surface due to solutes disrupted the hydraulic connection with the surface, resulting in decreased evaporation rates and cumulative evaporation.
A. Raisi Nafchi, J. Abedi Koupai, M. Gheysari, H.r. Eshghiazeh,
Volume 29, Issue 3 (10-2025)
Abstract
Rice is one of the most important crops and the primary food source for more than half of the world's population. The present study was conducted to compare the direct-seeded rice (DSR) of three rice varieties (Jozdan, Firuzan, and Sazandegi) using surface (DI) and subsurface (SDI) drip irrigation systems. The experiment was performed as a split–split plot arranged in a randomized complete block design with three replications in two years (2019 and 2020) in the research farm of Isfahan University of Technology in Najaf-Abad. According to the results of the variance analysis, the most suitable cultivar for DSR in the region (among the tested cultivars) is Sazandegi with a grain yield of 3400 kg/h-1. The results of this experiment showed that the amount of water consumed in DI was 20% less than in SDI. Also, DSR reduced water consumption by 40% compared to transplanted rice (TPR) in the region. However, the grain yield also decreased by about 45%.
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
A. Bagheri, A. Yadegari, K. Khaledi,
Volume 29, Issue 3 (10-2025)
Abstract
Wheat is a strategic crop, and boosting its production is vital. This study identifies key factors affecting wheat yield by estimating and selecting superior production functions. The research used panel data from crop years 1400-1385 in Isfahan province counties over 15 years, analyzed with EViews 10 software. Results showed water use had the greatest positive effect; a one percent water increase raised wheat yield by 0.41 percent on average. Cultivated area, fertilizer, seeds, and labor also had positive, significant effects. In contrast, air temperature had a negative effect, and agricultural machinery had no significant effect. Isfahan's arid climate and water's role in yield underscore the need for modern irrigation methods and better water use efficiency to improve production.
A.r. Jafarnejadi, A. Gilani, F. Meskini-Vishkaee, M. Hoseini Chaleshtori,
Volume 29, Issue 3 (10-2025)
Abstract
Rice, as one of the world's most strategic crops, plays a vital role in global food security. This study investigated the effects of different nutrition management approaches on yield and water productivity in dry direct-seeded rice cultivation (local Anbouri Red Dwarf cultivar) at Shavoor Research Station in Khuzestan Province. The experiment was conducted in a randomized complete block design with four treatments, including 1) Farmer's conventional practice, 2) Soil test-based fertilization, 3) Soil test-based fertilization + supplementary nutrition, and 4) 25% reduced chemical fertilizers + biofertilizers, with three replications. Results demonstrated that the supplementary nutrition (4270 kgha-1) and biofertilizer with 25% chemical fertilizer reduction (4356 kgha-1) treatments increased yield by 17% and 19.3 %, respectively, compared to conventional practice (3651 kgha-1). This improvement was primarily attributed to increased panicles per m² (10-14%) and enhanced nutrient uptake efficiency. The biofertilizer treatment also showed the highest water productivity (0.25 kg m-³) and the best benefit-cost ratio (23.25). Economic analysis confirmed that combining biofertilizers with 25% chemical fertilizer reduction significantly reduced costs while maintaining yield. These findings suggest that integrating soil testing with either biofertilizers or stage-specific nutrition represents an effective strategy for enhancing yield, improving water use efficiency, and reducing dependence on chemical inputs in dry-seeded rice cultivation. These methods can be recommended as sustainable models for farmers in arid regions like Khuzestan, which face salinity challenges and water resource limitations.
M. Tahvilian, S. Eslamian, A.r. Gohari, M. Jamali,
Volume 29, Issue 3 (10-2025)
Abstract
Time of concentration (Tc) is one of the key parameters in hydrological studies, playing a critical role in flood control structure design, runoff simulation, and water resource management. This study evaluates the performance of seven empirical equations—Bransby-Williams, California, Giandotti, Kirpich, Pilgrim, Rational Hydrograph (SCS), and Carter—in estimating Tc across 35 sub-watersheds in Khuzestan Province, Iran. To assess the accuracy, six sub-watersheds with reliable rainfall-runoff data were selected, and observational Tc values were calculated. The estimated results from the empirical formulas were then compared with observed data using statistical indices such as RMSE, ME, and the Nash–Sutcliffe Efficiency (NSE). The findings revealed that the Kirpich equation provided the most accurate and reliable estimates, with RMSE = 2 hours, ME = 0.44 hours, and NSE = 0.91. Subsequently, all seven models were applied to estimate Tc for the remaining sub-watersheds. Finally, a concentration time zoning map was generated, which can serve as a practical tool for hydraulic design, flood risk analysis, and optimal water resource planning in Khuzestan Province.
