Yayah Parvizi; Zahra Gerami; Mahmood Arabkhedri
Abstract
Introduction
The degradation of soil structure and reduced water infiltration into the soil are indicators of soil degradation, which lead to decreased stability and production quality, as well as environmental problems. Soil conservation methods are widely used to curb soil degradation processes and ...
Read More
Introduction
The degradation of soil structure and reduced water infiltration into the soil are indicators of soil degradation, which lead to decreased stability and production quality, as well as environmental problems. Soil conservation methods are widely used to curb soil degradation processes and improve soil structure and permeability. The effectiveness of these methods in enhancing these indicators and controlling soil degradation requires further study and evaluation. This research aims to investigate the stability of soil structure and soil infiltration rate affected by various soil management and conservation operations, and to compare them in the Razin Watershed area of Kermanshah Province.
Materials and methods
For this purpose, eight common reclamation and conservation operations in the study area were selected and evaluated. These operations include pit-seeding and seeding, rangeland audit plan - conversion of dryfarming to rangeland, rangeland audit plan - conversion of dryfarming to forage cultivation, almond tree planting alongside digging holes, land leveling, seedling planting, conversion of dryfarming to rangeland, forage cultivation and orchard, and forest area. For evaluation, random systematic sampling points were selected within the area of each operation and their corresponding control area for study and sampling. After digging profiles and sampling the soil, the laboratory measured and calculated soil aggregate stability indices, including Mean Weight Diameter (MWD), Geometric Mean Diameter (GMD), and the proportion of stable aggregates larger than 0.25 mm (WSA>0.25). The final infiltration rate was also measured in the operation areas and their controls using a disc infiltrometer. Finally, a statistical comparison of the mean values of MWD, GMD, WSA>0.25, and final infiltration rate in soil conservation operations and their control areas was performed using the T-test for independent samples and the Duncan test for comparing the means of these indices in various operations using SPSS software.
Results and discussion
The evaluation results showed that the lowest MWD index was related to land leveling and sapling planting at 0.15 and 0.35 mm, respectively, while the highest values at 1.9, 1.8, and 1.6 mm were related to 20-year-old almond planting, 10-year-old almond planting, and forest areas, respectively. Additionally, the highest WSA>0.25 index values were found in fodder cultivation, orchard establishment, and 10-year-old almond planting operations, indicating the formation of large and stable aggregates due to conservation operations. Among the eight operations studied, the 20-year-old almond planting operation showed the greatest improvements in MWD and WSA>0.25 indices. The results for the final infiltration rate indicated that soil conservation operations, particularly converting low-yield rain-fed lands to sapling planting and changing rangeland use to 10-year-old almond planting, led to the highest increases in final infiltration rate, at 21.8% and 16%, respectively, compared to the control.
Conclusion
Overall, soil conservation operations increased the relative share of larger soil aggregates. However, the soil infiltration rate index showed conflicting results, as factors other than the evaluated conservation operations also influenced water infiltration into the soil, necessitating further studies. Consequently, examining the role of management, especially land use management, is essential for sustainable soil resource utilization.
Hossein Salehi; Saeid Gharechelou; Saeed Golian; Mohammad Reza Ranjbari; Emad Mahjoobi
Abstract
Introduction
The rapid growth of the global population has led to a significant surge in water consumption across various sectors such as agriculture, industry, and domestic use. This heightened demand for water has profound implications, particularly in ensuring food security, meeting industrial needs, ...
Read More
Introduction
The rapid growth of the global population has led to a significant surge in water consumption across various sectors such as agriculture, industry, and domestic use. This heightened demand for water has profound implications, particularly in ensuring food security, meeting industrial needs, and providing safe drinking water. However, alongside this population growth, climate change has emerged as a critical factor, altering precipitation patterns and exacerbating water scarcity issues. In response to these challenges, there is a growing need to identify and manage accessible water resources effectively. This involves understanding the complex interactions between different components of the hydrological cycle, including surface water, groundwater, soil moisture, and atmospheric water. Hydrological models have emerged as valuable tools in this regard, offering insights into water availability, flow patterns, and quality assessment. These models play a crucial role in various aspects of water resource management, including mitigating environmental impacts, managing floods, and predicting future water stress scenarios. Additionally, they facilitate the analysis of watershed-scale dynamics and provide a basis for informed decision-making. Global Hydrological Models (GHMs) have gained prominence due to their ability to capture the interconnectedness of water systems across different regions. They enable researchers to assess and predict hydrological processes on a large scale, contributing to a more comprehensive understanding of water resource dynamics. Recent studies have focused on evaluating the performance of hydrological models, such as the Variable Infiltration Capacity (VIC) model, in simulating river discharge, soil moisture, and precipitation patterns. These evaluations often utilize various data sources, including satellite imagery, to validate model outputs and improve their accuracy. Moreover, the integration of advanced optimization algorithms, such as NSGA-II, enhances the modeling process by optimizing model parameters and improving simulation results. In light of limited ground station data in extensive watersheds, researchers increasingly rely on long-term weather data and modeling techniques to bridge data gaps and improve the accuracy of hydrological predictions. Overall, ongoing research efforts aim to refine hydrological modeling approaches, integrate diverse data sources, and develop robust strategies for sustainable water resource management in the face of growing population pressures and climate uncertainties.
Materials and methods
The Heblehroud Watershed, situated in the southern part of the Central Alborz mountain range, covers approximately 326,991 hectares and lies between coordinates 52° 13' to 53° 13' East longitude and 35° 17' to 35° 58' North latitude. It spans across Tehran, Mazandaran, and Semnan provinces. Mount Sefidab, with an elevation of 4047 meters, marks its highest point. The region features a semi-arid climate, receiving 272 mm of annual rainfall predominantly in winter and spring. The Heblehroud River, originating from the northern mountains, serves as the main drainage outlet. The semi-distributed hydrological model (VIC) was employed in this study to optimize the coefficient of efficiency (KGE) in simulating runoff on daily and monthly scales in the state of water balance. The study validated the VIC model using data from the Bonekooh station and applied the NSGA-II optimization algorithm to calibrate soil parameters from 1992 to 1996, considering the impact of watershed management. Soil data were obtained from the HWSD database available on the FAO website and categorized into 36 classes based on physical and chemical soil properties. Land cover data were sourced from the MODIS satellite database and classified into 17 categories according to the IGBP standard. Elevational bands are crucial in the VIC hydrological model for assessing soil water pressure distribution and surface runoff. In the Heblehroud basin, elevation differences can reach several thousand meters, impacting flow estimation. Therefore, using elevation bands derived from SRTM data is essential for accurate simulation. The accuracy of precipitation data from each database at the cell scale was evaluated using the IDW method.
Results and discussion
The results indicated that the APHRODITE database had the highest accuracy, while PERSIANN-CDR had the lowest. Additionally, the runoff simulation results demonstrated that the VIC hydrological model performed well in simulating daily and monthly runoff. The KGE efficiency index for simulated daily runoff was 0.78 during the calibration period and 0.76 during the validation period. Evaluating the simulated runoff using climatic precipitation data revealed that PERSIANN-CDR satellite precipitation data was less accurate in detecting precipitation amounts but performed better in simulating runoff. The KGE for this data on a daily scale was 0.64 during the calibration period and 0.77 during the validation period. The KGE index for APHRODITE precipitation data based on ground stations ranked second, with values of 0.62 and 0.75 during the calibration and validation periods, respectively. ERA5-Land precipitation data, which is reanalyzed data, ranked third with a KGE index of 0.50 during the calibration period and 0.66 during the validation period.
Conclusions
These findings indicate that climatic precipitation data can be effectively utilized in watershed management studies with low cost and appropriate accuracy, particularly in basins lacking a regular network or long-term data availability.
Alijan Abkar; hamzeh saeediyan
Abstract
Introduction
The involvement of people in the implementation of natural resource schemes ensures the success of these initiatives and can be very beneficial for the natural resources available in watersheds and stakeholders. Public participation in the implementation of natural resources operations ...
Read More
Introduction
The involvement of people in the implementation of natural resource schemes ensures the success of these initiatives and can be very beneficial for the natural resources available in watersheds and stakeholders. Public participation in the implementation of natural resources operations is crucial for achieving the goals and success of these projects. Emphasizing public participation in the conservation of natural resources is of great importance and credibility. Natural resources are an integral pillar of human life, and plans are developed and implemented to improve the environmental and social conditions of socio-ecological systems. Given that this research is focused on desert watersheds, the unique conditions of these watersheds are considered outstanding features of this study. This emphasis highlights the value and importance of people's organizations in desert areas, which usually have smaller populations compared to other climates. It also underscores the necessity of public participation for the success of natural resource projects across different climates in watersheds nationwide. Without public participation, the success of these projects, despite all environmental conditions, is very low.
Materials and method
In this study, the number of cooperative companies, rural development committees, micro funds, and rural funds in the entire Yazdanabad watershed was obtained. The distribution of different villages in the Yazdanabad watershed was then identified, and the activities implemented in them were investigated. Subsequently, meetings held by the PRA method in the villages of the Yazdanabad watershed were studied, and a comparison of NGOs before and after the implementation of the comprehensive natural resources management plan was carried out and analyzed.
Results and discussion
The results showed that there are 3 cooperative companies and 4 rural funds in the Yazdanabad watershed, and 16 development committees are active in this area. Almost every village has a development committee, and there are also 2 micro funds in the Yazdanabad watershed. The implementation of natural resources projects has a significant impact on the stakeholders of the watersheds, especially in desert areas, provided that people are the main basis of the implementation of this plan. By encouraging and modeling, 100% participation can be achieved to ensure the success of such projects. The results of natural resources plans before and after their implementation showed that these plans greatly impact people's livelihoods and the sustainable conservation of natural resources. People who are more aware of their natural resources are better able to protect them in their watershed without government assistance. The wide range of natural areas and the lack of human resources have caused the country's forests, rangelands, and watershed management organizations, as the main authorities and custodians of these fields, to have limited influence in all areas. This has led people to spontaneously meet their needs by forming and joining NGOs.
Conclusion
Moreover, the research results showed that the most common executive activities in all villages located in the Yazdanabad watershed were the formation of rural development committees and holding meetings regarding natural resources laws and regulations.
mohammad mahdi artimani; Hossein Zeinivand; Nasser Tahmasebipour
Abstract
Introduction
Due to the heterogeneity in watersheds and the non-linearity of hydrological behaviors, it is very complicated and difficult to fully understand the relationships within watersheds. Therefore, in evaluating these systems, a modeling process is necessary. Over the last few decades, hydrological/hydraulic ...
Read More
Introduction
Due to the heterogeneity in watersheds and the non-linearity of hydrological behaviors, it is very complicated and difficult to fully understand the relationships within watersheds. Therefore, in evaluating these systems, a modeling process is necessary. Over the last few decades, hydrological/hydraulic models have become essential in hydrology studies due to the development of programming languages and the provision of optimal and efficient algorithms for solving differential problems. The application of rainfall-runoff simulation models for flood events has been extensively studied by researchers in the field of water and soil protection, leading to the development of various models to simulate rainfall-runoff processes. One of the successful models in this field is the TOPKAPI-X model. This model was created in the 1990s at the University of Bologna by Professor Todini as a distributed rainfall-runoff model in watersheds. An important feature of distributed models is their ability to simulate components at any point of the watershed, allowing results to be extracted at any required point. Unlike lumped models that consider the entire watershed as a single unit, distributed models allow spatial distribution at any point in the watershed. Therefore, in this research, after calibrating and validating the TOPKAPI-X physical-distributed model in the studied basin, the model was optimized for flood estimation.
Materials and methods
The Gamasiab basin is located in the west of Iran, in the northern region of the Zagros mountain ranges, to the north of the Karkheh dam basin, and primarily within the territories of Hamadan and Kermanshah provinces. The mountainous regions of this basin are mainly concentrated in the northern and southern parts, while its lowlands and plains are mostly located in the middle and southeastern parts of the basin (Ministry of Energy, 2014). In this research, the TOPKAPI-X model was used to simulate floods in the Gamasiab watershed. First, the watershed boundary was delineated using a digital elevation model (DEM) with a resolution of 30 meters. Land use maps, soil texture, watershed network, and climatic components were entered into the TOPKAPI-X model. The outlet location of the basin (hydrometric station) was used to simulate the flow using the TOPKAPI-X distributed hydrological model. Continuous time series data on a daily time step were used in this rainfall-runoff model. Specifically, daily rainfall data from 13 rain gauge stations and temperature data from 4 synoptic stations during the statistical period (1999 to 2020) were used to simulate the flow. After running the model several times, the general parameters were manually adjusted each time until the optimal values of the general parameters were obtained by considering the appropriate values of the evaluation criteria (NS and Bias) for the basin.
Results and discussion
This research was conducted to analyze the flood discharge of one of the main sub-basins of the Karkheh dam basin using the TOPKAPI-X model on a daily time scale. In the TOPKAPI-X software environment, simulations were performed during the calibration period using input maps and observational rainfall, temperature, and discharge data. A visual comparison of the observed and simulated hydrographs allows for a general and quick evaluation of the model's accuracy. The graphical results of the comparison between the discharge generated by the TOPKAPI-X model with the calibrated parameters and the measured discharge in the Gamasiab basin were presented. The TOPKAPI-X model has the ability to estimate the maximum daily flow rates of the Gamasiab basin; however, some of the simulated flow rates are higher than the observed flow rates. Four criteria—NSE, R, BIAS, and RMSE—were used to evaluate the model. The evaluation results of the TOPKAPI-X model indicate the accuracy of flow simulation, with a Nash-Sutcliffe criterion of 0.697 during the calibration period (1999-2014) and 0.660 during the validation period (2015-2020) for the Gamasiab basin. Therefore, it can be concluded that this model has good performance for flow simulation.
Conclusions
The importance and usefulness of hydrological models for water resources management, understanding hydrological processes, and conducting impact assessment studies is clear. Hydrological models are crucial tools that enable scientists and policymakers to make informed decisions based on simulations of watershed behavior. Considering the increasing demand for water and the impact of climate change, hydrological simulation will be one of the essential methods for future water management. The results of this study showed that the TOPKAPI-X model has potential in simulating runoff in the selected basin. Due to the capabilities of the TOPKAPI-X distributed hydrological model, this software is recommended as a modeling tool for other basins.
Reza Norooz-Valashedi; Sedigheh Bararkhanpour ahmadi; hadigheh bahrami pichaghchi; Sara Mazloom Babanari
Abstract
Introduction
Climate is one of the environmental factors whose changes cause extensive alterations in different parts of the ecosystem and pose a significant threat to sustainable development. Temperature, a main element of climate, can affect the climate structure of any region through sudden, short-term, ...
Read More
Introduction
Climate is one of the environmental factors whose changes cause extensive alterations in different parts of the ecosystem and pose a significant threat to sustainable development. Temperature, a main element of climate, can affect the climate structure of any region through sudden, short-term, and long-term changes. In recent decades, the Earth has faced global warming, evidenced by climatic changes worldwide. One important consequence of global warming is the increase in extreme weather phenomena, such as sudden temperature changes, excessive heat, abnormal cold, heavy rains and floods, drought, and dust storms caused by the drying of wetlands. Climate extreme indices not only play an important role in investigating climate events on regional and global scales but also assist in climate modeling and decision-making for various sectors.
Materials and methods
In this research, temperature data from the MRI-ESM-2 model under three scenarios—optimistic (SSP1-2.6), average (SSP2-4.5), and pessimistic (SSP5-8.5)—for two periods, the near future (2021-2060) and the distant future (2061-2100), were used. First, historical data for the base period and scenario data for the future period (until 2100) for the studied climate model were obtained from the ESGF database. Then, using the R programming language, the time series of historical data and scenarios were extracted from the model for each desired station, and the statistical downscaling of the data was performed using the bilinear interpolation method at the level of the studied stations. The data were grouped based on the three scenarios in all studied stations, and RClimDex software was used to extract indices based on minimum and maximum daily temperatures. In this research, 16 extreme temperature indices for the studied area were calculated on annual and monthly scales, and trends and breakpoints in these indices were investigated using the Mann-Kendall trend detection test, Sen’s Slope test, and Pettitt mutation detection test.
Results and discussion
The results show a decrease in extreme hot events based on the SSP1-2.6 scenario, a decrease in indices related to cold and freezing days, and an increase in extreme warm indices based on the SSP5-8.5 scenario, observed in most areas of the province. Generally, the indices for the number of summer days (with a slope of 40-70%), tropical nights (45-65%), the length of the heat period (30-50%), and the length of the growing season (40-60%) showed significant increases. Conversely, the indices for the number of frost days (-20 to -80), ice days (-10 to -40), and the length of the cold period (-10 to -70) significantly decreased. The results of Pettitt's test indicated change points for increasing and decreasing trends in hot and cold extreme indices, respectively, in the 2040s (near future) and 2080s (far future). Therefore, to control extreme temperatures and their adverse effects on various aspects of human life, especially agriculture and water resources, strategies should be developed and implemented according to the needs of each region.
Conclusions
The results indicated more frequent sudden changes in temperature indices under the pessimistic scenario compared to the other two scenarios, affecting broader areas of Mazandaran province. There is a likelihood of sudden increases in hot extreme indices and decreases in cold and freezing days both in the near future (2030s, 2040s, and 2050s) and far future (2070s and 2080s). Overall, significant changes in temperature extreme indices were observed during the future statistical periods studied, with Mazandaran province expected to experience higher air temperatures and more frequent extreme heat events. These findings align with regional and global studies. The rise in temperature, particularly during hot months when precipitation decreases naturally, significantly impacts agriculture in this region, which is a major area for rice production in the country. These changes also affect the hydrological cycle downstream of the Haraz basin. Additionally, temperature fluctuations during winter and cold months can influence the timing of snow melting in the basin, thereby affecting peak flood flows downstream. Given these factors and the necessity of such research in understanding human activities, water resource management, food security, and human health, it is crucial to investigate the impacts of extreme climate events driven by temperature in future policy-making. Human societies must adapt and adjust based on these anticipated conditions. Therefore, studying the intensity, frequency, and timing of extreme events and raising awareness about them can effectively address environmental challenges and enable rational planning to mitigate and reduce these events.
Seyed Masoud Soleimanpour; S. Zandifar; O. Rahmati; M. Motamednia
Abstract
Introduction
Currently, drought poses a significant threat to food security due to reduced rainfall and increased agricultural demand. Its impact is particularly severe in arid and semi-arid regions, where populations are more vulnerable. Drought affects groundwater systems by initially lowering water ...
Read More
Introduction
Currently, drought poses a significant threat to food security due to reduced rainfall and increased agricultural demand. Its impact is particularly severe in arid and semi-arid regions, where populations are more vulnerable. Drought affects groundwater systems by initially lowering water supply, followed by a decline in groundwater levels and discharge. Compared to other types of drought, characteristics such as duration, intensity, and frequency alter groundwater systems.
Materials and methods
Given the critical need for drought assessment and monitoring, this study investigated drought conditions in 12 areas within the Daranjir Watershed from 2002–2003 to 2017-2018. The watershed spans approximately 50,736.44 km² across Yazd and Kerman provinces, with elevations ranging up to 1,857.90 meters. Highlands cover 58.99% of the area, while plains cover 40.99%. Data on groundwater levels from observation wells were obtained from Iranian Water Resources Research Organization (Tamab) and regional water organizations in Yazd and Kerman provinces. Average monthly groundwater level values were then extracted from maps using inverse distance weighting interpolation in MATLAB. Groundwater drought conditions were subsequently calculated based on the Groundwater Resources Index (GRI) in MATLAB.
Results and discussion
The GRI index calculations revealed severe droughts in Daranjir, Bardsir, and Qaryeh al-Arab deserts, with deficits of 81.38, 77.75, and 75.66, respectively. Qaryeh al-Arab experienced the longest drought, spanning 121 months, indicating the area's high intensity and prolonged drought conditions compared to other study areas. Mild droughts were the most frequent after normal drought across all study areas based on GRI index class frequencies.
Conclusions
Due to insufficient and highly variable atmospheric precipitation, drought is inevitable, especially in arid and semi-arid climates. Understanding drought severity and its impact on ecosystems is crucial for effective watershed resource management and optimal resource utilization. Continuous monitoring of groundwater levels due to drought and preparation of a comprehensive atlas for other watersheds in the country are recommended. Additionally, comparing drought conditions using appropriate models is essential. Short and long-term strategies are advised to mitigate this natural phenomenon, such as expanding greenhouse crop cultivation, utilizing drought-resistant crop varieties with high water efficiency, adopting pressurized irrigation systems, and implementing infrastructure projects to enhance groundwater and surface water storage, such as cement dams, reservoirs, and floodwater spreading systems in the study area.
Mohammadreza Kousari; forood sharifi; Alireza Majidi
Abstract
Introduction
In the context of climate change and global warming, the comprehensive management and productivity of water resources become increasingly important. Accurate measurement of existing water resources forms a critical foundation for effective water resource management. Precise measurements ...
Read More
Introduction
In the context of climate change and global warming, the comprehensive management and productivity of water resources become increasingly important. Accurate measurement of existing water resources forms a critical foundation for effective water resource management. Precise measurements enable better and more fundamental planning. Surface water, particularly flood-generated water in large and small watersheds, plays a significant role in Iran's water resources. A major challenge in the country's water resource management is the lack of sufficient runoff data, especially for smaller watersheds. The use of hydrometric devices for stable water level measurements can substantially address this issue, improving the collection of surface and groundwater data. Several methods have been developed for water level measurement, which can be categorized as contact or non-contact methods, depending on whether the sensor interacts directly with the water. These methods may record data either automatically or manually. Selecting the appropriate method depends on specific conditions, such as the range of liquid level changes, the physical properties of the liquid (e.g., density, cleanliness, vapor or particle content, corrosiveness), process temperature and pressure, chemical composition, and environmental factors like moisture.
Materials and methods
Non-contact methods offer significant advantages, including independence from fluid type and non-interaction with the fluid itself. Among these methods are image processing using cameras, ultrasonic sensors, infrared sensors, and laser-based techniques. This research investigates the efficiency of the Sharp infrared module model GP2Y0A02YK0F in measuring water level changes in both laboratory and natural environments. The module includes a distance measurement sensor consisting of a Position Sensitive Detector (PSD), Infrared Emitting Diode (IRED), and a signal processing circuit. It operates within a voltage range of 4.5 to 5 volts and a temperature range of -10 to +60 °C. The analog output of this module corresponds to the measured distance, producing values between 0 and 1023. When an object moves closer to the sensor, the output approaches 0, and as the object moves farther away, the output increases toward 1023. Data calibration is required to relate sensor readings to actual values. The sensor's measurement range is 20–150 cm, utilizing infrared light for distance detection. To evaluate its performance, a low-power data logger suitable for watershed environments was employed. Since the method requires a non-reflective surface, it was combined with a traditional float-based method. The mechanical setup includes a polyethylene tube housing the sensor, enclosed within a metal body to resist flood conditions. Laboratory experiments involved measuring water level changes across 10 stages, where sensor data (independent variable) and actual water level values (dependent variable) were collected. Polynomial fitting (first to fourth degree) was applied to establish relationships between variables. Additionally, 30% of the data was reserved for model validation.
Results and discussion
An inverse relationship between sensor readings and actual distances was evident: sensor output values decreased as distance increased. The correlation coefficients (R) for one- to four-term polynomial fits were close to one, indicating a strong alignment between sensor data and actual measurements. The RMSE ranged from 2.16 to 1.89 cm, improving with higher-degree polynomials. In laboratory conditions, the sensor estimated water level changes with a 2 cm error, which was reduced to 1.34 cm by increasing the minimum measurement range to 30 cm. Given its affordability, this sensor is suitable for applications where high precision is unnecessary. For higher accuracy, alternative sensors should be considered. However, in flood environments, issues such as the obstruction and adhesion of floating materials in the tube pose challenges, making this method unsuitable for flood channel measurements. Incorporating additional sensors, such as pressure or ultrasonic sensors, could enhance the device's capabilities.
Conclusions
Various methods have been developed for measuring water level changes. The selection of a method depends on environmental conditions, accuracy requirements, and cost considerations. Given the lack of extensive water level and flow measurement networks in Iran's watersheds, the approach proposed in this research can significantly contribute to water resource management. However, the reliance on floating components within the tube is a critical limitation, as flood-induced sediment can hinder float movement over time. Future research should focus on methods that eliminate the need for floating parts, thereby overcoming these limitations. Additionally, the results of other measurement techniques will be explored in subsequent studies.
Mohammad Reza Sheykh Rabiee; Hamid Reza Peyrowan; Peyman Daneshkar Arasteh; Mehry Akbary; Baharak Motamedvaziri
Abstract
Introduction
Climate change is one of the most important challenges that affects natural ecosystems and different aspects of human life. The effects of global warming on the hydrology and water cycle in nature are very serious, and knowing these effects quantitatively creates more preparation to deal ...
Read More
Introduction
Climate change is one of the most important challenges that affects natural ecosystems and different aspects of human life. The effects of global warming on the hydrology and water cycle in nature are very serious, and knowing these effects quantitatively creates more preparation to deal with its consequences. It is necessary to evaluate these changes in order to reduce their effects on the basin and formulate a suitable strategy to minimize their adverse effects. This study uses a combined model of SDSM and SWAT to investigate the effects of climate change on the amount of runoff and sediment in Karganrood watershed in Gilan province in Iran. The water measuring station (Mashin Khaneh) is located inside this basin and has a long statistical history. Also, the least amount of land use changes has taken place in this basin, which can better show the results of revealing climate changes on the amount of runoff and sediment.
materials and methods
In order to investigate the consequences of climate change on runoff and sediment, SWAT hydrological model was used. The SWAT model was calibrated and validated by the SUFI-2 algorithm by improving the simulation results of discharge flow and basin sediment. After the implementation of SWAT model, 109 hydrological response units (HRU) were extracted in five sub-basins. After 500 steps of simulation, finally 22 parameters in runoff production and 6 parameters in sediment production of Karganrood watershed were identified as effective parameters. Then, according to the values obtained from NS, R² and RMSE evaluation criteria, it was found that CanESM5 climate model has better accuracy and efficiency than MPI-ESM1.2-HR and NorESM2-MM climate models. By introducing the time series of daily average precipitation and temperature resulting from the output of the CanESM5 climate model and using the SDSM downscaling model, the runoff and sedimentation of the Karganrood basin on a monthly basis at the Mashin Khaneh hydrometric station in the periods of 2026-2050, 2075-2051 and 2100- 2076 for two scenarios SSP2-4.5 and SSP5-8.5. Simulated.
Results and discussion
According to the values obtained from NS, R² and RMSE evaluation criteria, it was found that CanESM5 climate model has better accuracy and efficiency than MPI-ESM1.2-HR and NorESM2-MM climate models. The results of the CanESM5 model indicate that precipitation, maximum and minimum temperature will decrease in all future periods based on SSP2-4.5. Also, the examination of CanESM5 model results in connection with SSP5-8.5 shows that precipitation will decrease in all future periods and the maximum temperature will increase in the period of 2051-2075 and 2076-2100. Also, the results of climate data in all three climate models and in both scenarios SSP2-4.5 and SSP5-8.5 showed that the period of 2076-2100 will be drier and warmer than other periods. In order to investigate the consequences of climate change on runoff and sediment using the SWAT hydrological model and by introducing the time series of average daily precipitation and temperature from the output of the CanESM5 climate model and using the SDSM downscaling model, the runoff and sediment of the Karganrood basin on a monthly basis at the station Car house hydrometry in the periods 2050-2026, 2051-2075 and 2076-2100 for two scenarios SSP2-4.5 and SSP5-8.5. Simulated. The results of the SWAT model showed that the runoff changes for the SSP2-4.5 and SSP5-8.5 scenarios will decrease and the sediment changes will increase in all future periods.
Conclusion
Using the output data of the CanESM5 climate model related to the sixth report and under the SSP2-4.5 and SSP5-8.5 scenarios and using the SWAT model, the amount of runoff and sediment in three time periods of the near future (2026-2050), medium (2051- 2075) and period (2076-2100) was carried out. The amount of sediment at the exit point of the Mashin Khaneh water measuring station showed an increasing trend. Also, the results showed that the observed stream flow limit does not match with the SSP2-4.5 and SSP5-8.5 scenarios in the future periods, but the observed sedimentation is compatible with the future periods. The data of the SSP2-4.5 scenario showed that discharge will decrease in all periods and sediment will increase in all future periods. The largest changes in discharge are related to the future period of 2076-2100 and amount to -56.7 percent, and the lowest number of changes in discharge are related to the future period of 2026-2050 and amount to -48.5 percent. The highest sediment changes are related to the future period of 2051-2075 and amount to 54.3% and the lowest amount of sediment changes are related to the future period of 2026-2050 and amount to 5.12%. Also, the results of the SWAT model based on the data of the SSP5-8.5 scenario showed that discharge will decrease in all periods and sediment will increase in all future periods. The largest changes in the flow rate are related to the future period of 2076-2100 and amount to -56% and the lowest number of changes in the flow rate are related to the future period of 2026-2050 and amount to -52.8%. The highest sediment changes are related to the future period of 2076-2100 and amount to 113.27% and the lowest amount of sediment changes are related to the future period of 2026-2050 and amount to 29%. It seems that the decrease in rainfall in the coming periods will cause a decrease in vegetation, especially in late summer and early autumn and with the melting of the remaining snow in the highlands due to the increase in temperature; The amount of produced runoff increases, which will increase the sediment produced in the basin.
Majid Mohammady; Mojtaba Amiri
Abstract
IntroductionHuman activities are at the core of global environmental change and Humans play a key role in global warming, land degradation, air and water pollution, rising sea levels, eroding the ozone layer, extensive deforestation, and acidification of the oceans. Soil erosion and degradation is a ...
Read More
IntroductionHuman activities are at the core of global environmental change and Humans play a key role in global warming, land degradation, air and water pollution, rising sea levels, eroding the ozone layer, extensive deforestation, and acidification of the oceans. Soil erosion and degradation is a natural phenomenon altering the relief of the landscape. Erosion is often capable of causing several on-site and off-site impacts. Erosion and soil loss are common in hilly areas, but their severity will vary depending on the geoenvironmental factors including, Steep sloping, geological characteristics, vegetation and climatic factors making it more vulnerable to erosion. One of he most important kind of erosion is badland erosion. The term of badlands currently refers to areas of unconsolidated sediment with little or no vegetation, which are useless for agriculture because of their intensely dissected landscape. Badland erosion is observed mostly in arid and semi-arid regions, and the interaction of precipitation with geological materials is responsible for the development of badlands in arid and semi-arid regions. Because soil erosion is a complicated process that is influenced by the properties of the land surface and the soil as well as by environmental factors, quantitatively accurate forecasts of soil erosion and susceptibility mapping are challenging. The main goal of this research is to map badland erosion suscepibility in Firozkuh watershed using frequency ratio model. Materials and methodsFirozkuh watershed was selected as study area because in this watershed, badlands are the most important contributors to soil erosion because of the condition of climatic, hydrologic, topographic, and reduced vegetation conditions, and as well as presence of susceptible soil and geology formations in this region. The first step in this research is to prepare distribution map of the badlands and determine their location on the map. This was done using Google Earth imagery and field surveys. The maps of condiioning factors were prepared from different sources and entered into the GIS environment. Digital Elevation Model (DEM) map with the cellsize of 30 meter was prepared using the elevation points and lines in the topographic maps prepared by the National Cartography Center of Iran. Slope aspect, slope degree, plan curvature, TWI and elevation classes maps was creaed using DEM map in ArcGIS10.3 and SAGA-GIS environment. The geology map of the watershed was extracted from the geologic map of Iran with the scale of 1:100000. River and road maps were extracted from 1:25000 topographic map and the distance from these features was calculated in ArcGIS10.3 environment. The land use of Firozkuh watershed was created from LANDSAT 8 images of year 2020 using a synthetic method. To map soil characteristics, 30 samples were taken from depth of 0-30 centimeter and analyzed in the laboratory. Aaverage annual rainfall map was developed using rainfall data from meteorological stations. After classifying conditioning factors maps, the weight of each map was calculated using the frequency ration model. In the next step, by combining the weights, the final badland erosion susceptibility map was prepared. The ROC curve and the area under the curve were used to assess the accuracy of the frequency ratio models. Results and discussionThe relationship between badland erosion and conditioning factors was investigated using the frequency ratio model. The results showed that the highest weight of the frequency ratio is related to the elevation class of 1710 to 2286 meters, rainfall 400 to 550, slope more than 35, northwest aspect, distance less than 1150 meters from drainage network, marl, limestone and shale formations, ranglands, Convex and concave slopes, clay 25 to 33%, silt 27 to 35%, hydrological group C, soil depth 57 to 120 cm, pH 7.6 to 1.8, TWI class 6 to 11. Accuracy assessmen of the freency ratio model was done using ROC and area under this curve. The area under the ROC curve was 0.71 that showed frequency ratio model is acceptable for badland erosion susceptibility mapping in the Firozkuh watershed. Despite its simplicity, the freqency ratio model provides acceptable results due to the creation of a logical connection between the badlands and conditioning factors. Other studies, including investigating the potential of underground water, landslide susceptibility maping, and the vulnerability to floods, have also been conducted with this model, and its accuracy has been confirmed. ConclusionsBecause of topographical, climatic and geological conditions, the badland erosion is a dominant phenomenon in the Firozkuh watershed. In this research, badland erosion susceptibility map was prepared using the frequency ratio model. Accuracy assessment showed that frequency ratio is a suitable model for badland erosion susceptibility maping in this watershed. The results showed that about 50% of this region has high and very high susceptibility to the badland erosion, so it is necessary to pay attention to this phenomenon and prepare a susceptibility map.
Mohsen Armin; Hamide Zahedikhah; Maleeha Mozayyan
Abstract
IntroductionCheck dams are simple and relatively low-cost structures that are widely used to control sedimentation in watersheds due to the lack of special materials and technology. These types of dams have the largest amount of watershed improvement operations in Iran. Therefore, considering the frequency ...
Read More
IntroductionCheck dams are simple and relatively low-cost structures that are widely used to control sedimentation in watersheds due to the lack of special materials and technology. These types of dams have the largest amount of watershed improvement operations in Iran. Therefore, considering the frequency of construction and as a result the cost of construction, it is necessary to investigate their performance in watersheds to identify their strengths and weaknesses. Evaluation of sediment trapping of check dams and correct selection of parameters affecting their sedimentation performance is the main goal of this research. Materials and methodsIn this research, the evaluation of check dams from the perspective of sedimentation performance in the Nehzatabad watershed in Kohgiluyeh county has been investigated. For this purpose, after determining the parameters related to the volume of sediments deposited behind 11 selected check dams and calculating their volume, the amount of sediment yield was first measured and then estimated by calculating three different sediment trapping coefficients. Finally, by calculating the sediment delivery ratio, the measured and estimated sediment yield was converted into its equivalent soil loss on the surface in the upstream sub-watershed of the check dams. Results and discussionThe results showed that the amount of specific sediment yield measured in check dams is from 0.001 to 1.08 and on average 0.13 tons per hectare per year. Considering the ratio of sediment delivery, which varied from 18 to 51 percent for selected dams, this amount of sediment yield is equivalent to 0.01 to 2.1 and an average of 0.3 tons per hectare per year of soil loss in the upstream sub-watersheds of check dams, which is a very small number compared to the figures presented for the average soil loss in most of Iran's watersheds. Taking into account different coefficients of sediment trapping, the estimated average values for specific sediment yield in check dams are 2.88, 7.46 and 0.87 tons per hectare per year, which are equivalent to 9.41, 30.5, 3.49 tons per hectare per year of soil loss respectively, which compared to the average amount of soil erosion in Iran's watersheds, seem more reasonable and logical numbers. ConclusionsConsidering the factors affecting the sediment trapping coefficient, it can be said that if check dams are built at a point in the waterway where the ratio of the storage capacity of the dam reservoir to the area of the sub-watershed upstream of the dams is higher, the sediment trapping coefficient in the dams will increase, which it is more favorable in terms of sedimentation efficiency. By examining the amount of sediment trapping coefficients in the investigated check dams in the Nehzatabad watershed, which are relatively low, it can be said that one of the reasons for the low coefficients is the reduction in the ratio of the storage capacity of the dam reservoir to the area of their upstream watershed. Therefore, if the scientific principles are not observed in the correct selection of the effective parameters for the placement of check dams, the implementation of such projects does not have the necessary and sufficient effectiveness, while the sediment measured in these dams and the soil erosion equivalent to it are a basis for the implementation of other watershed management measures are in watershed areas and if they are not accurate, It can lead to ineffectiveness of these measures and incorrect calculations.
yahya parvizi; Zahra Gerami
Abstract
Estimates made in the country indicate the annual waste of about one billion cubic meters of soil from the country's land resources. Although the economic valuation of this volume of soil resource loss is difficult, but considering the fragile balance of ecosystems in the country's land resources, it ...
Read More
Estimates made in the country indicate the annual waste of about one billion cubic meters of soil from the country's land resources. Although the economic valuation of this volume of soil resource loss is difficult, but considering the fragile balance of ecosystems in the country's land resources, it is possible to predict what irreparable and irreversible loss this volume of resource loss will bring to the production capacity and operation of these resources. shows Part of this soil loss is compensated and replaced by soil formation processes, and as long as the rate of erosion does not exceed the rate of soil formation, it is considered a kind of natural and inevitable process. Knowing the rate of natural replacement is necessary to monitor the changes in the quality and quantity of this natural resource and to know the process of its deterioration or recovery. On the other hand, every year, large amounts of the country's financial resources are spent on watershed management measures. Meanwhile, there is no quantitative regional standard for the design of these measures, as well as a practical guideline for evaluating the effectiveness of these measures. This standard, as well as the quantity of soil regeneration and renewability, is known in the world as tolerable soil erosion. In this article, a summary of the formation of this concept in soil science, factors affecting the value of T, as well as its calculation methods are introduced and evaluated. Also, a summary of research has been done and their results related to tolerable erosion and familiarization with different methods in this field, suggestions and research needs and optimal solutions for estimating tolerable erosion for the conditions of the country have been introduced.
Maryam Sabouri; Haydeh Ara; Mohammad Kia Kianian; Amin Salehpour Jam
Abstract
Over the past decades, excessive and unprincipled exploitation of watershed resources (soil, water, and vegetation) has reduced their health. The purpose of the present study is to evaluate the tourism value of geomorphotourist landscapes (case study: Hablehroud basin) using the Prolong model. Among ...
Read More
Over the past decades, excessive and unprincipled exploitation of watershed resources (soil, water, and vegetation) has reduced their health. The purpose of the present study is to evaluate the tourism value of geomorphotourist landscapes (case study: Hablehroud basin) using the Prolong model. Among the geomorphic sites in the Hablehroud region, 3 sites were selected and an identity card was prepared for each of the geomorphic sites. In this study, based on the Prolong model, a survey was conducted of a number of experts knowledgeable about the study area and visiting tourists (30 people) using a simple random sampling method. In this model, the tourism value of a place was measured by the average of aesthetic, scientific, cultural and economic values. After measuring the data, it was determined that among the three selected samples, the Vashi Gorge geosite with a tourism value of 0.54 and an average productivity value of 0.68 has the highest geomorphological tourism value. What has increased the value and importance of the Vashi Gorge is its uniqueness in the country, favorable and cool climate, geomorphological shapes and unique carvings on the rock wall of the gorge, as well as the waterfall view and the presence of a very beautiful meadow around this gorge. The Rudafshan Cave geosite with a tourism value of (0.41) was ranked second. The Khumdeh mineral spring with a hardness of (0.31) took third place. The assessments indicate that the tourism values of the geomorphological landforms of the Tangeh Vashi region are mainly due to the high value of the external beauty, cultural value, and scientific value of this landform. Factors such as difficulty of access, lack of appropriate welfare and service facilities, and lack of attention to geotourism have been effective in reducing the total calculated hardness.
Amin Salehpour Jam; Jamal Mosaffaie
Abstract
In this study, problem structuring and identification and prioritization of solutions to improve the health of the Kal-Aji watershed were carried out based on the DPSIR framework and non-parametric statistical tests. In the first stage, the drivers and pressures resulting in the health status of the ...
Read More
In this study, problem structuring and identification and prioritization of solutions to improve the health of the Kal-Aji watershed were carried out based on the DPSIR framework and non-parametric statistical tests. In the first stage, the drivers and pressures resulting in the health status of the Kal-Aji watershed and the related impacts were identified through a literature review, a visit to the watershed, interviews with experts from the departments of natural resources, environment, regional water, the Agricultural Jihad, the Agricultural and Natural Resources Engineering Organization of Golestan, faculty members of academic and research centers, and interviews with local communities. Then, a working group consisting of 26 stakeholders, local knowledgeable individuals, and experts knowledgeable about the issues and problems of the watershed began to determine solutions to improve the health of the Kal-Aji watershed and eliminate or modify the related adverse impacts. In the last stage, after forming the DPSIR table and identifying the various components of this framework in the Kal-Aji watershed, the importance of each of the variables categorized under the five DPSIR components was prioritized and determined. For this purpose, a Likert-scale questionnaire was used as a measurement tool. In this study, each variable was considered as an item, and the validity of the questionnaire was finally confirmed based on the opinions of experts. Also, Cronbach's alpha method was used to calculate the reliability of the measurement tool. In this study, the questionnaire variables were based on the multiple-response coding method, qualitative ordinal variables and matched the Likert scale (very low (1), low (2), medium (3), high (4), and very high (5)), so that the opinion of the expert working group members and the determination of the priority of the items were based on the Friedman nonparametric test.
kourosh shirani; Mehrdad Pasandi
Abstract
In this study the Sentinel-1 satellite data (ascending, descending, and combined modes) and PSInSAR technique were utilized to assess and map land subsidence risk in major watersheds of Isfahan Province, including Isfahan-Borkhar, Najafabad, Northern Mahyar, Southern Mahyar, and Kuhpayeh-Sejzi. The Sentinel-1 ...
Read More
In this study the Sentinel-1 satellite data (ascending, descending, and combined modes) and PSInSAR technique were utilized to assess and map land subsidence risk in major watersheds of Isfahan Province, including Isfahan-Borkhar, Najafabad, Northern Mahyar, Southern Mahyar, and Kuhpayeh-Sejzi. The Sentinel-1 radar data (2014 to 2023) were used, including ascending and descending imagery, to resolve displacement ambiguities caused by directional movement. Initial data processing involved co-registration of radar images to align pixels accurately and generate interferograms for phase change extraction. Persistent scatterers (PS) were identified using the Amplitude Dispersion Index (ADI) and phase stability analysis. Atmospheric and orbital errors were corrected using statistical models and inversion techniques to eliminate biases. Temporal analysis of ground displacement was conducted to calculate deformation trends, with data georeferenced for spatial interpretation. Validation was carried out by comparing results with ground-based data and independent sources. Final outputs included cumulative subsidence maps, annual subsidence rates, and risk zoning maps highlighting areas prone to land subsidence. The findings reveal that subsidence in the study area ranged from negligible to 55 cm over the nine-year observation period. Annual subsidence rates in parts of the Isfahan-Borkhar and Southern Mahyar watersheds reached 60 mm per year. Combining ascending and descending data improved accuracy and enabled the separation of vertical and horizontal displacement components. The highest cumulative subsidence was observed in urban and agricultural zones of Isfahan-Borkhar and in clayey sediment areas within Southern Mahyar. Hazard zoning maps indicate that Isfahan-Borkhar and Southern Mahyar watersheds have the largest areas classified as high-risk. Other watersheds predominantly exhibit moderate to low-hazard zones. The maps demonstrate a strong correlation between severe subsidence and land use (urban and agricultural areas) as well as geological features. Future research should focus on continuous monitoring and the development of predictive subsidence models to address this issue effectively.
Ehsan Fathi; MohammadReza Ekhtesasi; Ali Talebi; jamal mosaffaie
Abstract
Introduction and Objective: Understanding the damages and their causes in watersheds is a fundamental and essential step in watershed management, setting the stage for identifying suitable solutions and implementing targeted actions in these areas. The objective of this study is to explore management ...
Read More
Introduction and Objective: Understanding the damages and their causes in watersheds is a fundamental and essential step in watershed management, setting the stage for identifying suitable solutions and implementing targeted actions in these areas. The objective of this study is to explore management responses to improve the health of the watershed using the DPSIR approach.Materials and Methods: To this end, factors associated with each component of the DPSIR framework were initially identified through library research, resource review, and field visits to the watershed. A survey was conducted with 20 experts and 20 watershed residents based on the Likert scale, and then the Friedman test was used to prioritize the items from the perspective of experts and residents.Findings: According to the results, five driving forces in the watershed have created 34 pressures on watershed resources, which in turn have led to 11 unfavorable conditions in the watershed. These conditions have also resulted in 20 unintended impacts. Additionally, 32 management responses were proposed to improve the current situation. A matrix of relationships among the factors for each main component of the DPSIR framework and their prioritization from the viewpoints of both groups, experts and stakeholders, was conducted. The results showed a match of 40% among the top priorities, with a 50% match for driving forces, 69% for pressures, 80% for state, 75% for impact, and 84% for response.Discussion and Conclusion: The findings of this study indicate that the DPSIR approach serves as an effective framework for analyzing the causes and consequences of environmental and watershed resource issues. By identifying the root causes of problems, it provides appropriate management responses, enabling decision-makers and planners to develop comprehensive watershed management programs.
Asma Badameh; Mahmood Azari; Ali Golkarian
Abstract
Hydrological processes, as part of ecosystem services in drylands, are crucial for effective management and decision-making to preserve ecosystems. Quantitative assessment of ecosystem services is essential for defining various management strategies. Therefore, the objective of this study is to Spatial ...
Read More
Hydrological processes, as part of ecosystem services in drylands, are crucial for effective management and decision-making to preserve ecosystems. Quantitative assessment of ecosystem services is essential for defining various management strategies. Therefore, the objective of this study is to Spatial assessment and analysis of hydrological ecosystem services in the Neyshabur watershed. To this end, the InVEST model was used to determine the quick flow, water yield, erosion, and soil retention in the Neyshabur watershed. The model was calibrated and validated using precipitation, maximum, and minimum temperature data for the periods 1982-1989 and 1990-1993. Then, the monthly precipitation, minimum temperature, and maximum temperature maps were input into the model and executed. The results showed that quick flow is mainly influenced by precipitation. The average annual quick flow and water yield were 34.3 mm and 43.3 mm, respectively. The highest values of quick flow and water yield were observed in Sub-basin 1, while the lowest values were found in Sub-basins 4 and 5. In terms of water yield, these differences were mainly due to climatic conditions and land use types. Soil retention was higher than erosion in all sub-basins. Sub-basin 3, with the highest soil retention, has a greater potential for preventing erosion, while Sub-basin 4 has a lower potential. Forest, shrubland, and scrubland land uses have the greatest ability for soil retention. The findings indicate that Sub-basin 1 requires more precise management to prevent floods and optimize water storage, while forest cover protection is essential for maintaining soil retention services.
Maryam AriaSadr; Dariush Rahimi; Mehran Zand; Hadi Amiri
Abstract
Water quality is an important indicator of health. Determining water quality requires expensive tests. In this research, Support Vector Machine (SVM) and Classification And Regression Tree (CART) algorithms have been evaluated. To calibrate the techniques, 321 test samples of physical-chemical elements ...
Read More
Water quality is an important indicator of health. Determining water quality requires expensive tests. In this research, Support Vector Machine (SVM) and Classification And Regression Tree (CART) algorithms have been evaluated. To calibrate the techniques, 321 test samples of physical-chemical elements of Cham Anjir station (1969-2021) were used. According to the results of the correlation matrix, Total Hardness (TH) in water and Total Dissolved Solids (TDS) in water were selected to evaluate and select the optimal model. The results of the trend test showed that the concentration of both indicators has increased since 1985. The evaluation indicators of the SVM, showed that the best results of the SVM were obtained in the KernalLinear model and in the CHAID method (CART) algorithm at the 95% combination threshold. 10 rules were presented for estimating TDS, and 119 rules for estimating TH . The Validation of SVM and CART algorithms of observational and estimated data showed that MSE, MAE, R2 coefficients are not different in both SVM and CART models. But the estimations of TH in water and TDS. The amount of RMSE in SVM was less than 10%. Therefore, the SVM obtained better results compared to the CART for estimated data.
Mahmoudreza Tabatabaei; Amin Salehpour Jam; Jamal Mosaffaie
Abstract
In watershed areas, monitoring and assessing erosion and sedimentation processes are crucial, as these processes directly impact the quality and quantity of water resources. The design and construction of advanced systems, such as a specialized geographic information system for the country’s hydrometric ...
Read More
In watershed areas, monitoring and assessing erosion and sedimentation processes are crucial, as these processes directly impact the quality and quantity of water resources. The design and construction of advanced systems, such as a specialized geographic information system for the country’s hydrometric stations, can significantly enhance watershed management research.This study developed a specialized geographic system for managing and analyzing hydrological data using the C# programming language and open-source spatial libraries. The system uses SQLite as a data storage platform and employs Entity Framework 6 (EF6) and LINQ to facilitate data management and extraction. It can perform various spatial and descriptive queries and analyses, as well as statistical analyses and summaries from sedimentation data.The results can be summarized in two sections: the design and construction of the system, and the statistical analysis of sedimentation data from the Aras basin. The statistical analysis of sedimentation data (26,156 recorded data points until 2017) indicates that at the watershed scale, the average daily suspended sediment discharge is 11,814.95 tons per day, the average suspended sediment concentration is 4,185.68 mg per liter, and the average instantaneous flow discharge is 13.16 cubic meters per second.At the study unit scale, the average maximum and minimum suspended sediment discharge correspond to the Jolfa-Duzal unit (code 1105) with 10,312.33 tons per day and the Qareh Ziyaldin unit (code 1108) with 991.96 tons per day, respectively. Additionally, at the hydrometric station scale, the average maximum and minimum daily suspended sediment discharge correspond to the Jolfa station (code 807-19) with 571,697.82 tons per day and the Naur-Exit Neur station (code 0195-19) with 2.82 tons per day.This research aims to develop a national software infrastructure for managing sedimentation data and flow discharge from the country’s hydrometric stations.
mohammad Rostami
Abstract
To evaluate the scour depth around cylindrical piles of coastal protection structures under wave impact pressure caused by wave breaking, an experimental study was designed. The study aimed to analyze how variations in wave characteristics, including wave height and period, influence scour depth. It ...
Read More
To evaluate the scour depth around cylindrical piles of coastal protection structures under wave impact pressure caused by wave breaking, an experimental study was designed. The study aimed to analyze how variations in wave characteristics, including wave height and period, influence scour depth. It is important to note that this research focuses on breaking waves that directly impact the structure.In this study, a two-dimensional wave channel at the Coastal Engineering Laboratory of the Soil Conservation and Watershed Management Research Institute was used. To create shallow water conditions and ensure wave breaking at the pile location, as well as to assess the resulting scour depth, a sloped surface and a sediment reservoir were constructed in the middle section of the main channel. The sediment reservoir, with a depth of 0.35 meters, was installed upstream of the metal sloped surface and filled with sand sediments. A polycarbonate cylindrical pile was positioned at the center of the sediment reservoir.The wave channel was filled with water to depths ranging from 0.4 to 0.5 meters, and waves of varying heights and periods were generated using a wave paddle system. Through trial and error, the exact wave breaking location and the pile’s position relative to it were identified. A total of 34 experiments were conducted under initial water depths ranging from 0.4 to 0.5 meters. Wave heights varied between 0.05 to 0.14 meters, and wave periods ranged from 2 to 7 seconds. After each experiment, scour depth at the pile location was captured and measured using imaging techniques.The findings of this study revealed that wave breaking resulted in a 2.37-fold increase in scour depth and erosion compared to the passage of a regular wave near a cylindrical pile structure.Therefore, marine structure designers must carefully consider this issue.
Rouhangiz Akhtari; Hamidreza Hajipoor; Mojtaba Saneie; Mohammadreza Gharibreza
Abstract
This study experimentally evaluates the performance of individual check dams in mitigating flood peaks using a 1:10 scale physical model of Sijan stream, testing 90 scenarios under controlled laboratory conditions. The research systematically examines how stream characteristics (number of check dams ...
Read More
This study experimentally evaluates the performance of individual check dams in mitigating flood peaks using a 1:10 scale physical model of Sijan stream, testing 90 scenarios under controlled laboratory conditions. The research systematically examines how stream characteristics (number of check dams and their sediment conditions) and inflow parameters (peak discharge and hydrograph time base) influence flood control effectiveness. Results demonstrate that check dams reduce peak discharge by 5-16% and increase time lag to peak by 17-21%, with performance highly dependent on flood magnitude and duration. For floods with return periods increasing from 2 to 10 years, the peak reduction efficiency decreases from 16% to 5%, revealing structural limitations against higher energy flows. The hydrograph time base emerges as a critical factor - when exceeding the watershed's time of concentration, peak mitigation drops from 17% to 5% and time lag decreases from 35% to 8%, indicating reduced effectiveness for prolonged flood events. These trends are attributed to flow dynamics: larger floods overwhelm structural resistance, while extended durations lead to control saturation and steady flow dominance. The study develops three robust empirical relationships (R² = 0.81-0.92) through dimensional analysis to quantify check dam impacts on hydrograph modification, providing practical tools for watershed management. However, the derived equations require site-specific calibration for application beyond the Sijan stream due to their dependence on local channel geometry and roughness characteristics. These findings offer valuable insights for designing check dam systems, highlighting their conditional effectiveness and the importance of considering both flood magnitude and duration in watershed management strategies. The research contributes to improved flood control planning by quantifying performance limitations under varying hydrological conditions.
