Prioritization of Watershed Flooding Using the TUFLOW Hydrological Model and FRI-EO_Learn Smart Method

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Amir Sheikhzadeh Asadi, Navid Jalalkamali, Amir Robati


The effects of human activities and climate changes, which appear in the form of changes in the vegetation of desert areas, or agricultural fields in semi-arid climates, can change the nature of flood propagation downstream, especially in the urban areas of a basin. Drainage should be effective. In this study, in order to extract rainfall-flood relationships in an urban area of Vahdatiyeh, the sum of hydrological relationships as well as numerical and hydraulic models were used until the use of vulnerability index and zoning. By examining the question of whether the changes in the volume and form of flood propagation in an urban catchment basin can reduce part of the infiltration of water into the soil by changing the shape, speed and depth of the flow in the river network of that basin, which Following the development of impervious surfaces of urban use or soils with minimal vegetation in the upstream flood basin (increasing the runoff coefficient), should it compensate? The hypothesis of this study is based on this model that increasing the water level in the rivers, as long as the water level in the aquifer is lower than the height of the river bed, has no effect on the amount of infiltration from the river into the soil. Extraction of the volume and type of flow distribution in the upstream of Vahdatiyeh city, which is the center of flood entry from two waterway branches, was done by the method of regional analysis and the extraction of floods with a historical and at the same time probable return period. The TUFLOW numerical model was used to prepare the basic flow simulator. In order to prepare a structure for determining sensitive areas in flooding, from the processing of hundreds of Sentinel-2 satellite images for the period from 2016 to 2021 in preparing the NDWI index as a standardized measure of changes in water structures as well as land cover, and a detailed geological layer on Machine learning method and EO method were used as the basis of classification. The land structure layer was chosen as the criteria for classifying areas in determining the priority of flood risk. With the assumption that the increase in nutrition will be done only if the flood channels expand in a historical event. In this way, in this study, from the equations for determining water losses, under the title SCS-CN with a cumulative distribution function for limiting conditions, the amount of water storage capacity in the soil at the basin level, using standard layers of depth and impermeability in Two possible conditions of a similar flood were implemented, and we calculated with different flow loss figures. Determining and separating the effect of the effective range of feeding and losses in this method was done using a three-dimensional model with 22 vertical layers of MODFLOW code. The results of this research show that to determine flood-prone areas, the basic criterion should be the geological diversity in the simultaneous analysis with the agricultural development of the region. Using the images of sentinel satellites, it is possible to determine the classified intervals to receive the most changes in the NDWI index. These spatial intervals better determine the decision-making limits for the implementation of flow diversion structures, and even the limits of cultivation in order to restore the climate against droughts resulting from agriculture. In the upstream of Vahdatiye city, the elevation zone number 1 of the land structure class, which is in direct contact with the urban area and the flood-prone area, does not show the figures and numbers resulting from vegetation changes at least in the 5-year period. The reason for this issue can be explained by the agricultural activities in this area, or at least the fact that the mentioned area is downstream to receive surface water resources. But the scattered parts of the east are considered to be the main cause of the flood. In other words, unstructured agriculture has been effective in flooding the steep and higher areas of the study catchment area. Therefore, in the implementation of flood control plans, priority should be given to this part of the coordinate boundaries. Also, the results show that there are 2,831 man-made user units in the first class at a distance of 100 meters from the floodplain in Vahdatiye city. The first class specifies residential and commercial units.

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