Comparison and Geographical Analysis of Runoff Risk in Urban Crossings (Case Study: Four-Regions of Kerman City)

Abstract
City is a complex geographic space where all its components act in a systematic manner, so that the disruption of any of the components of the system causes the whole problem. In addition, the global climate change and urbanization expansion, the frequency and severity of natural disasters, and the resulting damage have grown substantially. The runoff of streets and alleys is one of the natural disasters in many modern cities of Iran, which has caused many challenges due to the intensity and the time for reaction. Prioritizing the different areas of the watershed basin will help in terms of the degree of vulnerability of water pollution to the targeting of urban plans and their effectiveness in sustainable urban development. In this research, using the AHP Fuzzy model based on statistical analysis, the geographic (natural and human) indicators affecting the low and road runoffs of streets and alleys were identified in four districts of Kerman during the years 1391 to 1395. Then, using the ArcCN-Runoff in the ArcGIS environment, risk maps were drawn up in these areas. Finally, the analytical-descriptive form was compared. Spatial distribution map of runoff of sub-basins and determination of runoff of streets and alleys in different regions of Kerman showed that Region 3 has the highest risk of flooded roads in the city.
Introduction
In recent decades, due to the expansion of urbanization and immense physical growth, the acceleration of land use changes, the change of roof coverings of buildings with impenetrable materials in Kerman, urban runoff from atmospheric precipitation has multiplied several times. With increasing peak runoff run, and its occurrence in shorter time, the risk of flooding of passages in the areas of concentration of the watershed of this city has increased. Therefore, this study is to divide the different areas of the watershed of the city of Kerman into smaller hydrological units, which can be studied accurately in the complex manufacturing process, runoff concentrations, and the identification of the spatial and geographical distribution of the flood risk of road flood in the four different districts of the city. The results of this study will help to better manage the city and improve urban life. The following is a brief overview of some of the most important researches in this area.
Materials and Methods
All information layers of the factors and complications of the standard maps for four regions of the city of Kerman were projected based on the UTM image system of the northern zone 40, and the reference elliptical base of WGS1984. For this purpose, at the beginning of the work, the boundary of the research domain (Kerman city) was considered based on country divisions. Given the availability of Landsat7 images (with a resolution of 15 and 30 meters), these images were used to update some layers needed for maps 1: 25,000. By specifying a set of criteria, each criterion is to be represented as a layer of the map in ArcGIS. The layers that represent the urban planning criteria affecting surface runoff are named as criteria maps. Once the criteria are specified, the map of each of the criteria is processed and prepared in the ArcGIS environment.
Studies in this paper were done in three levels. At first, urban planning criteria affecting runoff were determined and weighted; then, at the level of four areas of the city of Kerman, maps of spatial distribution of flood risk maps were mapped, and finally compared and ranked.
This research is applied in terms of purpose, and is based on analytical-statistical and analytical-descriptive methods. In order to collect information from the present research, documentary studies, libraries, fields, reference to the municipality database and meteorological organization statistics are available in the ending sheets and related articles; therefore, the tools used in this research is: Viewing and Fixing. In this research, the Matlab software for the weighting of the effective parameters in the creation of runoff, SMADA software for estimating the rainfall return period, and finally, ArcGIS software to show the spatial distribution of runoff flooding at the quadratic level Kerman city were used.
In several studies, SCS model based the C & CN was used for planning and management of urban runoff, indicating the performance of these models to estimate runoff altitude in urban areas. The reason for choosing the CN model in this study was its dependence on the SCS model, the simplicity and precision of its results, the conditions of the watershed of Kerman, and the quantity and quality of available meteorological statistics. This model is commonly used for small metropolitan basins, natural basins and for basins where there are no measurement data from Dubai (as in the scope of this research); in addition, the curve number is a model predictor that it records well environmental environments and is an approved method widely accepted in the United States and other countries.
Discus and Results
Finally, using ArcGIS, permeability maps and applications were prepared and using SCS relationships, a runoff height map was developed for sub-basins in district 1 of Kerman. As seen from the runoff height map of Kerman area (1), sub regions 11, 4 and 7 of this area with a runoff height of 71 mm are considered as the most problematic sub-basins for the highest risk of runoff, while the sub-basin 2 and 5, respectively, with a height of 48 and 45 mm runoff at the lowest runoff risk in this area.
Finally, using ArcGIS, permeability maps and applications were prepared and using the SCS relationships, a runoff height map for the sub-basins of Region 1 was prepared. As seen from the runoff height map of Kerman 1, sub regions 10, 11 and 7 of the urban area with the highest runoff rates of 81, 79 and 78 mm are considered to be the most problematic sub-basins for the highest risk of runoff. Sub-basins 2 and 6, respectively, with a height of runoff of 48 and 53 mm, are at the lowest risk of runoff in the area, respectively.
Finally, using ArcGIS, permeability maps and applications were prepared and using the SCS relationships, a runoff height map for the sub-basins of Region 1 was prepared. As seen from the runoff elevation map of Kerman area 3, sub regions 20, 11, and 18 of this area, with a rate of 83, 82 and 81 mm runoff, are considered as the most problematic sub-basins for the highest risk of runoff. Sub-basins 14 and 5, respectively, with a runoff height of 55 and 58 mm, are at the lowest risk of surface runoff.
Finally, using ArcGIS, permeability maps and applications were prepared and using the SCS relationships, a runoff height map for the sub-basins in Region 4 was prepared. As seen from the runoff elevation map of the 4th district of Kerman, sub regions 3 and 12 of the urban area with a runoff height of 82 and 81 mm, respectively, are the most problematic sub-basins for the highest risk of runoff, and sub basins 8 and 9, respectively, with a runoff rate of 55 and 56 mm, is considered to be at the lowest risk of surface runoff.
Conclusion
The results of the study indicate that Region 3 has the highest risk of urban flood congestion. The results of this study indicate that the most problematic runoffs in the streets of area 1 are: Mahmood Akhlaghi streets, Piranshahr martyrs, Shahid Rajaie, Danesbaz 6 boulevard, Khond Khordouh Blvd, Abbaspour Blvd, Firoozabadi 4, 11, 20 and 18 Shahid Bahonar, Bastani Parizi 3, Shohada, Mirzazadeh Kermani, Fath Ali Shahi, Imam Khomeini, Dadbin 2 and 3, Mahdieh 48 and 58, Sayedi Blvd, Managing Director 37, Shahid Nazarizadeh, Palestine 11, and Firoozeh 13.