فهرست مطالب سارا پرویزی

The amount of sediment and suspended materials, along with flowing water, is one of the important concerns in the design of hydraulic structures, such as channels, valves, and turbines of dams. This issue is very important from other aspects, such as maintaining the quality of soil in agricultural lands, addressing environmental issues, and managing water resources for drinking and industry. Satellite images, are used to estimate and monitor the water quality of rivers (especially the concentration of suspended load), the sources of pollution, and their movement. They cover a large area of the study area simultaneously, and they also record the spectral reflection of terrestrial phenomena. They have high efficiency. In general, research conducted in the field of the relationship between the spectral reflectance of water (recorded in satellite images) and the concentration of suspended load shows that there is a correlation between the red and infrared wavelengths with the concentration of suspended load. This correlation can be used as an indicator in the evaluation of these bands and to estimate the amount of suspended load concentration. The proper method to find the local model of suspended sediment concentration is to use field data collected during satellite imaging. In this article, the estimation of suspended sediment using Sentinel-2 satellite images in a narrow river has been discussed.

In this research, the estimation of suspended sediment concentration using Sentinel-2 satellite images in low latitude rivers has been investigated. In order to investigate the correlation between the spectral reflectance of the Sentinel-2 image bands and the concentration of suspended sediment, the statistics of the concentration of suspended sediments at the Polchehr station, located in the Gamasiab River of Kermanshah province, in a five-year period (1394 to 1398) were used simultaneously with them. For this purpose, a range of different amounts of sediment has been used, from a concentration of 0.44 mg/liter to 118.86 mg/liter. Out of the total of 24 images suitable for the days of measurement of suspended sediment concentration, four images were removed due to cloudiness, and two images with abnormal reflection higher than the others. Finally, 18 satellite images related to floods were used, of which 12 images (70% of the data) were used in the calibration stage, and 6 images (30%) were used in the validation stage. In this study, the pixel values of the images corresponding to the hydrometry data of Polchehr were extracted in two modes: single band and band ratio. Suitable regression models (linear, exponential, and polynomial) were fitted, and the accuracy of these models has been checked. Finally, the type of algorithm governing the concentration of suspended sediment in Gamasiab River was determined.

In this research, 8 bands of the Sentinel-2 satellite were used as single bands and band ratios. The results showed that the concentration of suspended sediment in the Polchehr station varied from 0.44 mg/liter to 118.86 mg/liter. Based on the results, it was found that dates with higher reflectance values had higher measured suspended sediment concentrations. The highest amount of reflection from the water surface was observed in band five (703 nm) and B8A. Also, from the obtained models, it was found that in the case of a single band, better results were obtained than when the band ratio was used. The exponential model related to band 5, which had a higher correlation with all sediment values, and the coefficient of determination was obtained as 0.83. To evaluate the results of the current research, the root mean square error of the evaluation index was used, and its value was 33.95 for the 5-fold band. It was found that the modeling of the suspended sediment parameter was done with proper accuracy. The results of the present study showed that satellite images can be useful for evaluating water quality monitoring. In addition, this study showed that Sentinel-2 can be used as a suitable tool for estimating suspended sediment concentration with acceptable accuracy in small-scale watersheds and flood conditions.

The results showed that the Sentinel-2 satellite images and the equations obtained in the present research are suitable for calculating the suspended sediment concentration in the Gamasiab watershed of Kermanshah province. Based on the results, it was found that nine models for the studied area had acceptable and suitable coefficients of determination and error values. Among the obtained models, it was found that better results were obtained in the single-band mode than in the mode where the band ratio was used. Also, the results showed that the exponential model related to Band 5, which had a higher correlation with all the sediment values, can be used to estimate the suspended sediment concentration from Sentinel-2 satellite images in the Gamasiab watershed of Kermanshah province when it is possible to collect no field data. The present study will be useful as a reference for future research in investigating and estimating suspended sediments using satellite data. In addition, considering the importance of suspended sediment in water quality and its effects on the environment and economy of the region, the use of suspended sediment estimation methods using satellite data can be used as a fast and efficient way to monitor water quality in narrow rivers.

Soil erosion and related problems i.e. sedimentation are associated with significant issues and problems on the environment and agriculture, including economic losses, reduction of water quality, storage capacity of reservoirs and agricultural production, among which watershed activities play a prominent role in reducing the amount of soil erosion and sediment yield. For this purpose, in the present research, the watershed management activities were evaluated on the amount of sediment yield, using the Connectivity Index in the Gonbad paired catchment of Hamadan province. In this regard, firstly, the estimation of the continuity index was conducted in the erosion plots installed in the control and impacted watersheds during the events that led to sediment production. Then, a regression relationship was established between the data of the Connectivity Index and the erosion plots sediment yield using the Connectivity Index in order to estimate the rate of sediment yield of control and impacted watersheds. Finally, the impact of watershed practices on the degree of sediment yield was measured by comparing the estimated sediment in control and impacted areas using the Connectivity Index. The results showed that the average amount of sediment produced in the sample and control sub-basins is 0.003 and 0.005 tons per hectare, respectively, that is, the amount of sediment in the sample sub-basin is 45% less than the control sub-basin, and this difference is due to the effect of watershed management operations in the sample sub-basin.

Water resources management, especially in watersheds without statistics all data, requires the recognition of hydrological processes, especially runoff, as one of the most important and most practical phases of the hydrological cycle. The aim of this study was to determine the efficiency and usability of the SWAT model in simulating the water balance of the Fakhrabad watershed. For the initial implementation of the model, the data required for the model implementation include meteorological data (precipitation, minimum and maximum temperature, relative humidity, and wind speed), baseline maps of the region (digital elevation map, land use, slope and soil map) and monthly discharge data of Fakhrabad hydrometric station. Were used. After the initial implementation of the SWAT model, the output was called to SWAT-CUP software for calibration and validation after sensitivity analysis, the model was implemented to determine the sensitive parameters and the results were reviewed. Calibration and validation were performed for the period 1998-2014 and the accuracy of monthly runoff simulation using the coefficient of determination (R2) and Nash Sutcliffe (NSE) for the calibration phase of 0.73 and 0.71 and for the validation phase of 0.54 and 0.53 was obtained. Acceptable values were also obtained for the uncertainty assessment indicators. P-factor and R-factor were 0.56 and 0.65 for the calibration period and 0.54 and 0.68 for the validation period, respectively. The final results showed that on average of 67% of precipitation enters the atmosphere through evapotranspiration, 23% enters the canals as surface run off and subsurface flow. The results show the efficiency of the SWAT model in simulating the water balance of Fakhrabad watershed and helps to more accurately programing water resources in this basin.

In recent decades, flood-spreading and artificial flood recharge have been used at the proper time and place for optimal utilization of floods in arid and semi-arid regions. The importance of these projects in Iran is mainly due to the excessive use of groundwater resources and recent droughts, which have rapidly decreased the level of underground aquifers. Therefore, in a country like Iran, which is regarded as an arid and semi-arid region, performing such projects is essential for water resources management and flood control. Evaluation of the performance of watershed management projects in different countries worldwide has a history of more than 80 years. Thus, this study sought to determine the long-term effects of this project on flood control and underground water recharges, especially in dry years, through a technical investigation of the Mehriz flood-spreading project.

This study used technical evaluation methods to evaluate the Mehriz flood-spreading project, which was carried out in two ways: statistical analysis and fieldwork. In the first method, all necessary data were collected and analyzed. In the second method, field visits to the project were made, the pros and cons of the note plan were identified, and the technical evaluation of the plan was performed. This way, the discharge of qanats was investigated before and after applying the water-spreading project.

The comparison of average annual discharge in Fakhrabad River's hydrograph before and after the project shows that from July to November, the flow rate in each period was equal to zero, and from December to April, the river's flow rate was less in the pre-project period than what it was in the post-project period. Moreover, the average discharge rate in the month before the project began was lower than the rate reported after the project finished. Also, the average rate of post-project discharge in May and June was less than the rate reported for the pre-project period. The study's results indicate that while most pre-project floods occurred in late spring and early summer, the post-project floods occurred in late winter and early spring.

As mentioned earlier, this study investigated the effect of the Mehriz flood-spreading project on qanat discharge. According to the study's results, Baghdadabad's qanat in pre-project years was less than that of control 1 (Ibrahim Abad) and control 2 (Henza). During the years since the project was implemented, these qanats' discharge rate was higher than that of both control qanats. A comparison of the three-year mean discharge of the Baghdad qanats in May, August, and February in two ten-year periods before and after the implementation of the project showed that these qanats' discharge rate was increased in pre-project years. Therefore, implementing the flood-spreading project has helped increase the volume of water in those qanats. Also, the result of the statistical t-test showed that this aqueduct's flow rate has increased in pre-project years.The changing trend of the Khairabad qanat's discharge in Yazd indicated the positive effect of implementing the flood-spreading project on the qanat's discharge in post-project years. On the other hand, the result of the t-test for Mohammadabad qanat before and after the implementation of the project suggested that the qanat's discharge rate in pre-project years was less than the rate reported for the post-project years. Also, a hydrological comparison of the average quarterly discharge rates of the qanats with those of the control qanats pre and post-project years showed that the discharge rates of Khairabad and Mohammadabad qanats had gone through a downward trend from 1987 to 2007, indicating no effect of the flood-spreading project on increasing the discharge rate, which is considered as one of the drawbacks of the flood distribution plan. This could be attributed to the fact that the project area is located in a place where flood water naturally spreads and nourishes most channels. Moreover, diverting the water of the Fakhrabad channel and spreading the flood water to a particular place prevents some downstream qanats (such as Mohammadabad) from being fed by the floodwater, which, in turn, may upset the floods' balance and negatively affect the behavior of the basin's residents.

Estimation of the amount of sediment material (carried by a specific stream) is one of the main topics of sediment research. Sediment research is important in many engineering projects such as planning and design of water storage resources, morphology and changes in river bed, annual sediment estimation for reservoirs, sustainable irrigation, coastal protection, channel dredging, and etc.The evaluation of the sediment occurrences, and estimation of the sediment carried by rivers has a special importance and it is necessary to develop new methods with easy application for estimating the sediment transport. This study seeks to develop a method to be able to predict the amount of bedload with classification and regression trees and compare with some well-known empirical formulas such as Meyer Petter Muller, Shields, Einstein Brown, and Shoklitch. Measured data from Yazdakan station, located in Qotour River in Azarbayjan Gharbi, northwest of Iran, has been used in this research. It is a mountainous river with gravel bed that carries a high volume of sedimentation. A set of 76 field measurements over 8 years was used in modeling after verification and refinement. The model was trained on 80 percent of data and tested on the remained 20 percent. The best input contained whole four variables; flow discharge, suspended sediment discharge, flow depth and velocity, and the output was bedload discharge. The quantitative results of the best Decision Tree include MAE = 2134, RMSE = 2668 and % R = 89. The results of Regression Trees demonstrate more accuracy in the prediction of bedload compared with empirical formulas.

The increase in greenhouse gases in recent decades and the resulting increase in temperature have upset the balance of the planet's climate system and caused widespread climate change in most parts of the world. In this study, first the SWAT model was calibrated for Jamishan watershed. The calibration and validation stages, NS and R2 coefficients were 0.6, 0.61, 0.52, and 0.54, respectively. According to the results of sensitivity analysis in the region, it was found that among the 20 parameters affecting runoff, the curve number was the most important parameter. Then, the values of temperature and precipitation for the next period based on the climate change scenario were subscaled with the outputs of the HadCM3 general atmosphere rotation model for the three scenarios A2, B1 and A1B using the LARS-WG model. Later, in order to simulate the watershed runoff, the data were introduced to the SWAT model and the results showed that the runoff in the statistical period of 2015 and 2026 increased by 6, 7 and 6% respectively compared to the observation period in each scenario A2, A1B and B1 and this shows the impact of climate change on runoff in the near future from 2016 to 2026. This study showed that changes in meteorological parameters will lead to significant changes in hydrological regime such as watershed runoff. Increasing rainfall and temperature are likely to cause floods in the region in the future.

Floods are a natural phenomenon that causes heavy losses of life and property and ‎human societies every year and people have accepted it as an inevitable event. In this research, to predict the flooding in Sardabrood basin ‎ SWAT hydrological model was used. Information needed for this research, ‎including topographic maps, land use, soil data, and meteorological data, data about daily ‎rainfall, temperature, and flow rate were prepared beforehand. SUFI2 program was used for model ‎calibration. After the calibration and optimization of the model, validation of the model in the ‎study area was done. The calibration of the model wad performed for the years 2003 to 2009 and validation was performed for ‎the years 2010 to 2013. To analyze the results of statistical indicators R2, bR2, and Nash Sutcliffe ‎coefficient were used. After model calibration the respective coefficients were, 0.77, 0.63, and 0.77  and ‎the respective validation coefficients were  0.79, 0.76, and 0.71. The sensitivity results of 31 parameters that are influential on runoff water showed that fixed parameters of groundwater base flow, its time, and the minimum amount of water necessary for groundwater base flow are more sensitive than other parameters. Number Sardabrood parameter curves were used for flood basin. Sardabrood basin was divided into 24 areas to study the flooding pattern. Finally using the above mentioned models it was concluded that sub basin No. (6)  had the first-rank with runoff 123.05, ‎‎sub basin No. (10) had the second rank with runoff in terms of flooding and sub basin No. 1 with a 12.33 has the least amount of runoff.‎

Flood is a natural disaster making the heavy humanistic and economic damages each year in most parts of Iran. In this research, the SWAT model performance in flood prediction and sub-basin priority was investigated in terms of flooding in Araz-Kose watershed in Golestan province. To calibrate the model, SUFI2 was applied. The calibration and validation were done for the 1991-1998 period based on the data of 2001-2009. After validation, the indices (R2, bR2, and NS) were estimated. They were equal to 0.81, 0.81 and 0.73 for calibration and 081, 0.78 and 0.64 for validation, respectively. The sensitivity analysis results showed 13 effective parameters. The curve number (CN2) was determined as the most effective parameter. For studying the flooding in a watershed, the Araz-Kose watershed was divided into six parts. Based on the obtained results from the SWAT model with different CN and F indexes (with/without considering the sub-watershed), the sixth sub-basin with 22.4% decrease in discharge was chosen as the most effective region in flooding. Meanwhile, the other sub-basins including 4, 1, 3, 5 and 2 had more flood potential, respectively.

A large part of Iran is considered a semi-arid regions and water is a limiting factor for human activities in these areas. One of the ways to eliminate seasonal shortages of water is using groundwater. Underground dams can be used for storing and using underground water, which can be used to improve the management of existing water resources and increase the productivity of these resources.1 . In this research, at first,by using the knock-out criteria, by means of Boolean logic, including geology, land use, slope and fault and using Bollini logic, suitable areas were identified for the construction of underground dams.2. - In the second stage,by using ANP analysis network methods and by using experts' questioning method, other important criteria were chosen to select the most appropriate areas for underground dams including distance from the road, distance from the village and .... In underground dams, subsurface flow has many importance. Therefore, in this research, the SWAT model was used to simulate water flow and subsurface flow in the area and For prioritizing the obtained areas, those areas with proper subsurface flow was identified. after evaluating of the weights of each parameter in the super decision software environment, it used to locate and prioritize the susceptible areas. Eventually, nine favorable points were identified as optimum areas for the construction of a landmine.

Nowadays, drought is known as one of the environmental phenomena that has important impact on water quality. The aim of this study was to obtain a relationship between drought and water quality in Zayande-Roud watershed. With respect to the impact of droughton water qualityand also determining the type of water and its relationship with environmental factors, in this study, chemical characteristics of water were investigated using AqQasoftware. Then, chemical type of water resources and its relationship between drought and water quality was determined. The study area was Zayande-Roud River that has five hydrometric stations with 34 years common data. Two stations were located before dam and three stations after dam. In this period, using drought indices (SPI and RDI), dry and wet years were separated from each other, then maximum common dry and wet years were determined in five stations. Then, water quality data were compared in dry and wet years. Based on the results obtained, with the occurrence of drought, the concentration of ions in water has increased and in wet years the concentration of ions in water has improved. As example in Eskandari station, magnesium ion has increased by about 37% in dry years and the rate of sulfate ion in Pol-e-Zaman Khan station has increased by 56% in dry years. Water type in each station was sodium bicarbonate that can be related to geological factors.

Nematic liquid crystals doped with magnetic nanoparticles, called ferronematics, are among the new colloidal suspensions with critical magnetic properties. Dispersing magnetic nanoparticles in a cholesteric liquid crystal medium also leads to the creation of the other phase of anisotropic magnetic fluids known as ferrrocholesteric. In fact, the ordering behavior and some features of these new materials are drastically influenced by the presence of magnetic nanodopants. The transition field and orientational ordering depend on the volume fraction and magnetic moment of the dispersed particles as well as the external and material parameters such as magnetic anisotriopy and the cell thickness of a liquid crystal cell. The investigation of these new anisotropic nanomaterials is very important not only from the theoretical point of views but also practical application in nanotechnology. In this work we consider a ferrocholesteric cell with homeotropic anchoring conditions on the cell walls and soft anchoring modes on the ferrpparticle surfaces. Then, we study the stability of the system and transition to a feronematic state caused by exposure to a laser beam and under applied magnetic and electric fields.