پژوهشی
Mohammad Hossein Rezaei Moghaddam; asadollah hejazi; Mehdi Mezbani
Abstract
In this study, in order to identify the spatial distribution of soil erosion and sediment production in Sarab Sikan basin, the RUSLE model, GIS and remote sensing technology are used. First, using meteorological data, soil and digital elevation model with a size of 10 meters, each of the factors of erosion ...
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In this study, in order to identify the spatial distribution of soil erosion and sediment production in Sarab Sikan basin, the RUSLE model, GIS and remote sensing technology are used. First, using meteorological data, soil and digital elevation model with a size of 10 meters, each of the factors of erosion erosivity (R), erodibility (K), slope and slope length (LS) and soil protection (P) in the Arc GIS was calculated in Arc GIS. Sentine2 satellite sensor was also used to extract and prepare the vegetation factor of the basin (C) in ENVI 5.3 software environment. Finally, by combining these factors, the amount of basin erosion was calculated and the amount of sediment produced in the basin was obtained by different methods of sediment delivery ratio (SDR). The results showed that the amount of erosion in the basin is varies from 0.003 to 248.4 t ha-1y-1 and the average erosion in the basin is 22.3 t ha-1y-1. Among the model factors, LS factor with a correlation coefficient of R2 = 0.92 showed the highest share in soil erosion. Also, the SDR ratio was calculated by different methods between 0.12 and 0.36, which after combining with the erosion map, the sediment yield of the basin was estimated. The average sediment yield by Boise method is 2.8 t ha-1y-1, which is closer to the amount of station sediment with an average of 1.65 t ha-1y-1 compared to other methods.
پژوهشی
Kaka Shahedi; mahtab forootan danesh
Abstract
Simulation of the rainfall-runoff process in a watershed is highly important from the point of view of hydrological issues, water resources management, river engineering, flood control structures and its storage. Rainfall-runoff estimation using a distributed hydrological model and the technique of GIS ...
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Simulation of the rainfall-runoff process in a watershed is highly important from the point of view of hydrological issues, water resources management, river engineering, flood control structures and its storage. Rainfall-runoff estimation using a distributed hydrological model and the technique of GIS has become possible, practical and common. The Wetspa model is a distributed model simulating runoff and water balance that is performed at different time scales including hourly or daily basis. In this research, the discharge is simulated using Wetspa model in the Ghorichay watershed. This watershed (as one of the sub-watersheds of Gorganrood) with an area of 2481.5 ha is located in the south of Ramian city in Golestan province. The data used by the model are land use maps, soil texture, digital elevation model, precipitation, evaporation, temperature and discharge (for calibration and validation of the model). Calibration of 13 parameters was performed manually and automatically for 7 years at the beginning of the statistical period and model validation was performed for a period of 5 years. The results of the model evaluation show the accuracy of discharge simulation and very good agreement between the simulated data and observations based on the Nash-Sutcliffe criterion of 67.21% in the calibration period and 76.34% in the validation period. Also, the discharge calculated by the Wetspa model for the whole watershed was 28.31%, which in comparison with the observed discharge of 30.12% indicates a good simulation of the model.
پژوهشی
Geomorphology
roya panahi; Mitra moshashaie; Meysam moshashaee
Abstract
First, to extract the morphological variables of the channel, such as the Entrenchment Ratio (ER) index, Width/Depth ratio (W/D), curvature coefficient, channel slope, in the software environment. HEC-RAS (version 5.0.7) was extracted and the bed materials obtained from field investigations were collected. ...
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First, to extract the morphological variables of the channel, such as the Entrenchment Ratio (ER) index, Width/Depth ratio (W/D), curvature coefficient, channel slope, in the software environment. HEC-RAS (version 5.0.7) was extracted and the bed materials obtained from field investigations were collected. And according to the difference of the slope of the river of Mereg River was divided into four reaches and the curvature coefficient and radius of curvature were calculated in the GIS environment (version 10.5) for each section. 44 cross sections were used to calculate the river in level II Rasgen. The results of this study show that Mereg River is in the first reach in the F6 class. in the second and third reaches of the river in the C6 class, and in the fourth reach of the river in the B6 class. The characteristics of cross sections in category F6 are high bed slope, low subsidence index and less developed flood plain, and the potential of side erosion is very high. In the cross sections of category C6, the amount of slope has decreased, in addition, the Entrenchment Ratio (ER) index has increased and the floodplain has expanded, and the controlling effect of vegetation on the stability of the range is very high. cross sections in category B6, the slope is lower than other intervals, the Entrenchment Ratio (ER) index is average and finally the erosion potential of the side is low.
پژوهشی
hydrogeology
Fariba Esfandyari Darabad; Zeinab Pourganji; Raoof Mostafazadeh; Maryam Aghaie
Abstract
Floods as destructive natural hazards need to be predicted in accurate way through evaluation of the hydrological response of watersheds to the effective input rainfall. Due to the variety of rainfall-runoff models, it is very important to choose a suitable model that can simulate the hydrological behavior ...
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Floods as destructive natural hazards need to be predicted in accurate way through evaluation of the hydrological response of watersheds to the effective input rainfall. Due to the variety of rainfall-runoff models, it is very important to choose a suitable model that can simulate the hydrological behavior of the watershed. In this study, various rainfall-runoff transformation methods have been evaluated, including triangular, broken triangular, variable triangular and SCS-curvilinear unit hydrograph methods in Nenekaran watershed, Ardabil province. In this regard, the Wildcat5 hydrological model have been used to this purpose. The precipitation amount at the 25-year return period was calculated using Cumfreq software. After preparing the land use map of the study area using satellite images, the area of each land use in the area has been calculated using ArcGIS software. The precipitation value and the time of concentration were considered constant during the simulation procedure. The results showed that the SCS method had the highest runoff of 44.50 cubic meters per second. The minimum time to the peak was 2.19 hours and the variable triangular method had the lowest peak flow rate. The simple triangular method has a maximum time to peak of 4.51 hours, which shows the great difference between the hydrograph of the SCS method and the other three methods. The difference in the nature of the methods, the watershed condition, and the suitability of estimating tc and CN parameters should be considered in rainfall-runoff transformation methods.
پژوهشی
habibeh Abbasi; Mohammad Taghi Aalami; Mohammad faraji
Abstract
This article aims to analyze the trend of monthly, seasonal and annual changes in the flow and sediment of the Mordaghchai. located in East-Azerbaijan province. In this regard, using non-parametric methods, discharge and sediment data of Gheshlagh-Amir hydrometric station have been analyzed in three ...
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This article aims to analyze the trend of monthly, seasonal and annual changes in the flow and sediment of the Mordaghchai. located in East-Azerbaijan province. In this regard, using non-parametric methods, discharge and sediment data of Gheshlagh-Amir hydrometric station have been analyzed in three time scales: annual, seasonal and monthly. The modified Mann-Kendall test was used to analyze the trend of gradual changes in discharge and sediment data. Also, the Sen's slope estimator was used to estimate the slope of the trend line and the non-parametric Pettitt test was used to investigate the abrupt changes in the discharge and sediment time series. The modified Mann-Kendall test was used to analyze the trend of gradual changes in discharge and sediment, and the Sen' slope estimator test was used to estimate the slope of trend line. Also, Pettit test was used to investigate abrupt changes in the river discharge and sediment time series. The results show that annual, monthly and spring, summer and winter discharges significantly decrease at the level of 5%. The annual and all-season sediment load data significantly decreased by 5%. There is a significant decrease in sediment load in all months except March, April and October. The results of the Pettitt test show that the average annual discharge in the period after the breaking point (1998) has decreased by 45% compared to the period before the breaking point. Also, the average annual sediment load after the breaking point (1996) has decreased by about 52% compared to the previous period.
پژوهشی
hydrogeology
Mousa Abedini; Sajjad Javadi; Raoof Mostafazadeh; AmirHesam Pasban
Abstract
Today, soil erosion is one of the major problems of watersheds and agricultural areas and natural resources, which causes land degradation and decreases soil fertility. Therefore, the purpose of this study is to investigate the relationship between vegetation and geomorphic indices with the values of ...
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Today, soil erosion is one of the major problems of watersheds and agricultural areas and natural resources, which causes land degradation and decreases soil fertility. Therefore, the purpose of this study is to investigate the relationship between vegetation and geomorphic indices with the values of erosion and sediment in the watershed of Koot-e-Tootraghi basin, which was done by using the capabilities of GIS to extract the geomorphic characteristics of the basin. For this purpose, erosion and sedimentation rates were calculated using the modified Psiac model (MPSIAC). Also, in order to extract physiographic and geomorphic features including: TWI topographic moisture layers, SPI current strength, SLOPE slope, domain curvature, profile curvature and sub-basin plan curvature, from the height digital model with a spatial accuracy of 30 meters, as well as other layers used in the MPSIAC model including1:25000 topographic maps, 1:100000 geological maps were used. According to the box diagram, the indices related to curvature have little changes in the studied area. Also, the indices related to curvature have little changes in the studied area. Based on the results, there is a positive and significant correlation of 0.47 (p-value less than 0.01) between the standard index of vegetation cover and topographic humidity index. In addition, there is a significant correlation (0.63) between waterway power index and slope. It was also found that the relationship between the slope and the normalized index of vegetation has an inverse and significant relationship (0.48) (p-value less than 0.01.).
پژوهشی
Tahereh Nasr; hadi Abdolazimi
Abstract
Understanding the levels of urban resilience and planning to reduce the effects of various risks has a key role in managing urban crises. The purpose of this research is to identify areas with different resilience in the eleven districts of the Shiraz metropolis in order to deal with the flood crisis. ...
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Understanding the levels of urban resilience and planning to reduce the effects of various risks has a key role in managing urban crises. The purpose of this research is to identify areas with different resilience in the eleven districts of the Shiraz metropolis in order to deal with the flood crisis. The current research is based on the Fuzzy-AHP method and uses the criteria of the level of relief (sub-criteria of the density of firefighting centers, emergency, medical centers, hospitals, law enforcement, and Red Crescent), the state of residence (sub-criteria of the density of temporary accommodation places, population density and spaces Occupied), access status (sub-criteria of the density of arterial type and width of passages), worn texture and equipment placement status, identifies areas with different levels of resilience (weak, medium, good and very good). Examination of the level of relief showed that there is a weakness of relief in areas far from the city center. Therefore, it is suggested to increase the emergency services in the neighborhoods and areas far from the center of Shiraz in these places. In terms of criteria and sub-criteria examined in this research, weaker resilience was generally seen in the east and northwest of the city. The results of this research can be considered by executive managers in the phase of crisis management prevention and preparation.
پژوهشی
Hydrogeomorphology
Davoud Mokhtari; Amir Heshmati
Abstract
Knowing the subsurface structures is one of the ways to access underground resources, and knowing the characteristics of alluvial sediments is very important for exploitation, management and control of underground water. Shahryar plain located in the west of Tehran city and south of central Alborz, which ...
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Knowing the subsurface structures is one of the ways to access underground resources, and knowing the characteristics of alluvial sediments is very important for exploitation, management and control of underground water. Shahryar plain located in the west of Tehran city and south of central Alborz, which supplies an important part of Tehran city's drinking water, is covered with Quaternary alluvium. The purpose of this article is to determine the thickness of these alluviums. There are different geophysical methods to estimate the thickness of different layers of the earth to determine the characteristics of alluvial deposits, including the type, depth, thickness, etc., of this plain, the data of electric soundings includes: 12 profiles and 186 sections, received from the regional water organization, geological maps, and data DEM used. After checking and validating the data, by choosing the normal kriging interpolation method with exponential variogram, the alluvial thickness and topography maps of the underlying layers include: alluvial thickness map, evaporite sediment surface topography, tuff and igneous rocks topography, The topography of the bedrock of the region, the thickness of evaporite sediments and the topography of the conglomerate surface of the region were preparedin in GIS with the highest accuracy. Then horizontal and vertical characteristics of these deposits were investigated. The results showed the maximum thickness of the alluvium is up to 350 meters in the center And near the edge of the plain, the thickness of alluvium decreases so that it is about 10 meters in the west and southwest.
