Background and Objective According to Article 45 of the Constitution of the Islamic Republic of Iran and Article 2 of the Law on Fair Water Distribution, rivers are a national asset. They are in possession of the Islamic State. Therefore, the government is obliged to st
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Background and Objective According to Article 45 of the Constitution of the Islamic Republic of Iran and Article 2 of the Law on Fair Water Distribution, rivers are a national asset. They are in possession of the Islamic State. Therefore, the government is obliged to study and determine the bed and river boundaries, and if it recognizes the aristocracy in the bed and their area for disturbing water or electricity issues, to evacuate or tin and suppress them. Today, due to the increase in the economic value of land and the demand for land construction in lands along rivers and waterways, unfortunately, the process of using the riverbed has increased, which is a threat to access to safe water and its protection for future generations. Occupying rivers is associated with reduced land use and land use change. This disrupts the natural flow of the river, resulting in flooding and social, economic, and environmental damage. It is not possible to manage water resources, especially flood management, without knowing and analyzing the flow of rivers, flood zoning, and determining their bed boundaries and boundaries. At present, a land survey is being conducted to determine the extent of the floods and to determine the extent of the riverbed. This method is very time-consuming and expensive to perform. In this regard, using satellite imagery and aerial photographs instead of terrestrial mapping can be helpful in speeding up studies and reducing costs. Much research has been done in our beloved country of Iran and the world on the use of satellite images in various fields. In particular, several studies have used satellite imagery to study the changes in land use in watersheds and to study the morphological changes of the river. As noted, research has been conducted on the use of satellite imagery in hydrological studies and watersheds, but for the first time in this study, it is possible to use satellite imagery to map the river and extract its cross-sectional areas for flooding and riverbed delimitation. Has been studied. In recent years, the bed of the Ardak River above the Eradak Dam has been extensively occupied and altered. This has led to an increase in the number of floods and a decrease in the quantity and quality of water in the Ardak Dam, which supplies part of Mashhad's drinking water. For flood management and quantitative and qualitative protection of the Ardak dam, flood zoning and determination of the Ardak riverbed is necessary. At present, the ground mapping must be done first. Land surveying to map the river and extract its cross sections requires a lot of time and money. Therefore, the aim of this study was to investigate the possibility of using satellite images with a resolution of 28.28 m instead of terrestrial mapping to increase the speed of work and reduce the cost of studies of water projects and projects and river engineering.Materials and Methods ASTER satellite imagery and HEC-GeoHMS software were used to draw the catchment area and extract its physical parameters. The existing riverbed map and its margin were prepared and added to the land use map of the basin as a new layer. The HEC-HMS hydrological model was used to simulate precipitation and runoff. First, a metering and validation model was used for five rainfall and runoff events. The precipitation histogram for different return periods was then introduced to the HEC-HMS model based on the basin concentration time. The execution and flood model were simulated with different return periods. The river's geometric information was extracted in transverse sections from both terrestrial mapping and satellite imagery using the HEC-GeoRAS appendix. Information from river flow modeling in HEC-RAS software was transferred to the GIS environment through HEC-GeoRAS extension and in the mentioned environment, flood zoning and riverbed boundary determination were determined by two methods of using land mapping information and using satellite images.Results and Discussion The results indicate that the flooding area and the determination of the riverbed can be done by using satellite images with a resolution of 28 × 28 m. In this case, the statistical indicators of the mean relative error and regression correlation coefficient were 13.2 and 92%, respectively. If cross-sectional crossings are taken at several points along the river route and replaced by cross-sections obtained by satellite imagery, the accuracy of flood zoning and riverbed delimitation will be enhanced by the use of satellite imagery. If at a distance of 150 meters and at a distance of 8 km, 47 cross-sections are located and grounded and replaced in the HEC-RAS model by cross-sections obtained from satellite images, the error of using the satellite imagery method for flood zoning and riverbed delimitation Will be reduced to 8.1%.Conclusion It is possible to use satellite images with a quality of 28 × 28 m to determine the river bed limit. This method is associated with the average relative error and regression correlation coefficient of 13.2% and 92%, respectively, which can be reduced by 8% with ground cutting.
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