1.5. Resilience Exercise

Here attached is the technical report for flood resilience exercise: Flood Resilience Report


Introduction

    Flood in urban area are more frequent and more powerful due to overpopulated place, climate change and so on. In order to decrease the risk, we had construct several obstacles for the stream. But sometimes, the constructions are not good enough, so we need to focus more on a risk culture through adaptation, mitigation, feedback and so on.

    Providing a framework using different parameters seems to be a reliable way to reduce the flood damages indeed, the evaluation of economic, environmental, social and institutional level has to be evaluated. The relationship between the urban structure and the nature of interaction is crucial. By doing this, a community can prevent the damages caused by the flood.

Arc-GIS

    About the given files which are available, here is an overview of it using the Arc-Gis software:

Figure 1: Flood map, Urban area and Domain on Arc-GIS

    The flood map corresponds to the event of 1994 which occur in the city of Nice.

    So there is different type of Urban land-use such as Education as well as Food Etc and the main objective of this exercise is to know what type of building is flooded by different water level, for instance for a water threshold of 10cm, which and how much building are impacted in order to provide mapping with vulnerable area.

    First of all, we need to divided the flood map in 6 classes to have an overview of which structure if flooded by the water, as it’s shown on the figure below:

    The large red part below is the Mediterranean Sea.  In order to know which building is flooded, different manipulations are necessary:

 

    Transform the classes of the flood map into a raster layer using the raster calculator:

 

Con (“FloodMap_elements_0_PolygonT” > 0.1,1)

 

    Then, the transformation of this layer into Polygon must be done. By this way, we know the polygon surface for the water influence.






Figure 2: Overview of surface water during the flood (Units: meters)

    At the end, we have to extract the Polygon (water influence) that overlay the Buildings area. The Clip tool will be quite useful for this.

    The final map and the result for the “Building under 0.1m” are present below

Table 1: Building features under 0,1 meters

                                      Figure 3: Final flooding map

FRI building and city scale

Building scale

    The excel file provided in the data is tables which describes the dependences in terms of water, electricity etc in each urban function like Housing, Working building.

    We must fill it with our own feeling, the weight and the availability are here the main element. The weight gives some priority to certain critical requirement based. The final result for the flooded area are present on the graph below

Figure 4: Flood Resilience Index (FRI) for building scale

City scale

    Another excel file is provided by the supervisor in order to have a global view on a city scale. We need to evaluated in one side the availability of the FRI and on another side the weight of this parameters. 

    5 parameters are discussed and evaluated for the assessment using 91 indicators. The proportion of those indicators is as follow

- Natural: 3% 
- Social: 10% 
- Economic: 18% 
- Institutional: 30% 
- Physical: 39%



    The mean value is around 3.14 which is too low for a city like Nice.

    Actually some indicators can’t be informing due to the lack of knowledge of some indicators meaning. 





                Figure 5 : Flood Resilience Index (FRI) for city scale



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charlotte SOULERAS,
19 Feb 2017, 10:29
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