Exposure, hazard and risk mapping during a flood event using open source geospatial technology

Abstract

After a flood event there is a need to delineate the hazard footprint as quickly as possible in order to assess the magnitude of losses and to plan for the relief operations. Delineation of such hazard footprint is generally hindered by the lack of geospatial data, technology and related software packages. This paper demonstrates the use of open source data and software packages which can be used to implement most recent technology available for flood hazard footprint delineation. This study utilizes open source software packages and web applications like Geographic Resource Analysis Support System, Quantum geographic information system and Google Earth to implement a complete process of hazard mapping using remotely sensed data which include preprocessing, mapping (both hazard and exposure) and accuracy assessment. In this study, Brisbane flood event of 2011 has been taken as a case study. For built-up extraction, the Landsat 7-band image has been transformed to a stack of 3-band image using vegetation, water and built-up indices. It has been observed by scattergram analysis that these transformations make vegetation, water and builtup classes more separable. Built-up area has been delineated using supervised maximum likelihood classification on the new 3-band image. For flood hazard mapping, thresholding of near-infrared band has been utilized along with the assistance of mid-infrared band to discriminate water from built-up classes. After delineating both exposure and hazard map, final risk map due to flood event has been generated to assess the urban exposure under the flood hazard impact.

A GIS-Based Approach for Flood Risk Zoning by Combining Social Vulnerability and Flood Susceptibility: A Case Study of Nanjing, China

“…Previous studies on flood risk assessment mainly emphasised physical vulnerability, ignoring social vulnerability to risks and spatial changes in these dimensions [ 17 , 47 , 48 , 49 , 50 ]. Rapid urbanisation and marketisation have increased the risk of flooding by overlapping spatial heterogeneity and social differentiation.…”

Spatial Assessment of 2014-flood Disaster and Extent of Associated Damages in Lower Chenab Basin, Upper Indus Plain, Pakistan

“…So far, 25 major oods have occurred in Pakistan since 1950 whereas in the past two decades the frequency of high ooding events has been increased (Hashmi et al 2012;Mahmood and Rahman 2019). As a result, individual, household and community vulnerabilitiy have been heightened (Aggarwal 2016). The changing demographic conditions, socioeconomic status and human economic activities in the ood zone have further intensi ed the vulnerability to oods (Ouma and Tateishi 2014).…”

“…Consequently, the individual, household and community vulnerabilities have been grown (Ouma and Tateishi 2014). The varying demographic conditions, socio-economic status and human economic activities in the proximity of active ood plain have further intensi ed vulnerability to oods leading to high risk (Aggarwal 2016;Mahmood and Hamayon 2021).…”

Triggering multi-actor change cascades: Non-representational theory and deep disaster risk management co-production

“…Governmentality and civic epistemologies. Foucault's concept of governmentality has been used in DRM research to explore how governments and related agencies produce social order through the techniques, rationalities and strategies they routinely deploy (Aggarwal, 2016;Fraser, 2017;Mustafa, 2005;Rebotier, 2012). Fraser (2017), for example, has used this idea to explore how the field of 'urban vulnerability' to climate risk has been constituted 'as a new problematic of urban governance, creating new technologies and subjects' (2836).…”