Spatial analysis of resilience against natural hazards with an emphasis on floods The Case study of districts of district one of Tehran city

A B S T R A C T
Flood risk is a multidimensional concept related to uncertainty and complexity. In urban areas, flood risk assessment is still challenging because flood risk analysis is usually not conducted in the combination of social and economic impacts, but exclusively in assessing economic damages that can be measured financially. Flood management involves reducing the effects and risks, but eliminating the effects and risks is almost impossible. The reason for this is our financial limitations and limited knowledge of us humans. One of the ways to reduce the effects of risks is resilience. Based on this, the main goal of this research is to identify the spatial distribution of the state of strength in the districts of the first district of Tehran. Therefore, to achieve the goal, the fuzzy method was used in GIS software. The results of the final index of resilience show that the first region, especially the south and the centre, had the best conditions. Areas 4 and 5 also had suitable conditions in their vicinity, but in comparison with the area, their area was less than one level in the category with suitable conditions. In general, these three regions (1, 4 and 5) formed a continuous pole. After District 1, District 6 had the best situation. Unlike area 1, the influence area of this area does not form a continuous area in other areas and only includes the area of area 6. Also, in general, the western areas (2, 3, 7 and 8) were somewhat worse than the eastern areas
Extended Abstract
Introduction:
Cities are dynamic systems resulting from the interaction of humans and the natural environment over time, and they need balance to maintain, evolve and develop. Any imbalance in the systems within the city (spaces and urban texture) and the systems outside the city (near and far Peri-urban and regional arenas) cause its instability. From earthquakes to floods, massive migrations to cyber-attacks, all cities are faced with a range of shocks and pressures (natural and human) which are considered as factors of instability of cities. The occurrence of these devastating disasters highlights the importance of creating an urban resilience system. Resilience is an approach in which the tolerance capacity and stability of conditions against accidents, threats and challenges are evaluated. One of the advantages of planning for urban resilience is that there is no need to focus on a specific model. Resilience in the form of flexibility allows it to respond and adapt according to the conditions of each city and its development plans. This issue causes intellectual creativity to be created to think of different ways of acquiring resilience, without being limited in a specific framework.
 
Methodology
The current research is applied in terms of its purpose and descriptive-analytical in terms of its method. After collecting the investigated indicators from the relevant institutions such as Iran Statistics Center and Tehran Municipality Information Technology Organization, according to their unit difference from each other, all the indicators were standardized according to their positive or negative. In the next step, the sub-indices of each of the dimensions were combined with each other through linear summation and the resilience index was obtained in each of the three dimensions. Then, the final index of resilience was obtained through the combination of three dimensions of resilience. On the other hand, the total score of three sub-indices (the distance from the river, the permeability of the land, and the slope) was determined under the title of the flood hazard probability index. Finally, through the geographic weighted regression model, the spatial influence of the final index of resilience in reducing the risk was obtained in each of the ten investigated areas.
 
Result and Discussion
Based on the flood risk index, it can be said that the eastern districts have a much better situation than the western districts, so that the districts 2 and 7 did not have favorable conditions in terms of any of the risk sub-indices, and accordingly, they were placed in the lowest category and the possibility of flood risk is very high in them. In other words, most of the area of these districts, in addition to the short distance from the river, had a high slope and most of them were built and considered impenetrable.
According to the economic resilience index, it can be said that district 10 had the most unfavorable situation. After that, districts 6 and 4 had an unfavorable situation. This is while Darabad River passes around these districts. Districts 5, 3 and 8 had average status. Districts 3 and 8 are near the Golabdareh River and district 5 is near the Darabad River. Districts 2, 7 and 9 are in good condition despite the fact that the river passed through them and they are subject to flooding. Finally, like its situation in all economic sub-indices, District 1 had the most appropriate situation in its final index as well.
According to the social resilience index, most of the studied districts had an average status; So that districts 6, 5 and 9 in the east of the region where the Darabad River passes through them and districts 2 and 7 where the Golabdareh and Darband rivers pass through them all had average status. Districts 8 and 3 (affected by Golabdareh River) were in very unsuitable and unsuitable conditions, respectively. Districts 4 and 10, where a river does not pass near them, were in good and very good condition. The results of this index show that the districts at risk had low resilience, and on the contrary, the districts that were further away from the source of risk, had much better conditions in the field of social resilience.
According to the final index of physical resilience, it can be said that the eastern districts 6 and 10 (under the influence of the Darabad River) and the western district 7 (under the influence of the Golabdareh River) had the most suitable conditions. After them, district 9 alone was placed in the next category. Districts 4 and 8 were also in the center of the region had average status; although no river passes through them, they are located between two rivers, Golabdareh and Darabad. District 2, in the westernmost position of the region (under the influence of the Darband River), had unsuitable conditions. The worst situation was related to the district next to it, i.e., district 3, through which the Golabdareh River passes. In general, it can be said that districts 2 and 3 did not have suitable conditions despite the river passing through them, but districts 6, 7 and 9 had much better conditions despite the river passing through them.
The results of the geographically weighted regression show that according to the location of the rivers, the slope of the land and its permeability in the districts of the region one, as well as the resilience of the districts, the western districts have more unsuitable conditions than the eastern districts and the resilience index has low and very low impact when the hazard occurs; Because in addition to the fact that most of the districts of this part had unsuitable resilience, they also had very unsuitable conditions in terms of the sub indicators of flood risk. On the contrary, in the eastern districts, even if the districts had an unsuitable situation in terms of risk indicators, instead they had good resilience conditions.
 
Conclusion
Most cities are places of high population density and man-made phenomena; for this reason, if there is no preparation to deal with disasters, in the disasters time, they will face many human and financial losses. Therefore, what is discussed today in the urban management is the resilience of cities, which is very important because it can easily affect the life of a city.
The final resilience index determined that most districts (2, 4, 5 and 10) had moderate conditions. No river passes through any of the mentioned districts, except for district 2, where the Darband River passes. District 8 in the center of the region, which is very close to Golabdareh River, had unfavorable conditions. The eastern districts 6 and 9 (under the influence of Darabad River) and the western district 7 (under the influence of Golabdareh river) had suitable conditions. district 1, despite being located in the center of the region and no river passing through it or not located at a very short distance from it, had an unfavorable resilience situation.
 
Funding
There is no funding support.
 
Authors’ Contribution
All of the authors approved thecontent of the manuscript and agreed on all aspects of the work.
 
Conflict of Interest
Authors declared no conflict of interest.
 
Acknowledgments
We are grateful to all the scientific consultants of this paper.