This study explores the different dimensions of flood risk, namely hazard, exposure, and vulnerability, and investigated the drivers of risk in different ecological regions of Ecuador. The assessment was conducted at the parish level, the smallest administrative scale, for three selected provinces of Bolivar, Los Ríos and Napo, representing not only the country’s three main ecological regions but also commonly affected territories due to flooding. Using automated flood detection procedure based on Sentinel-1 synthetic aperture radar data, flood hazard information was derived from flood frequency and flood depth for the years 2017, 2018 and 2019. The drivers of exposure and vulnerability were derived from scientific literature and further evaluated and complemented during a participatory workshop with over 50 local experts from the different regions. Centered on this exercise, an indicator library was created to inform the data selection from various sources and provides the basis for deriving a spatially explicit flood risk assessment using an indicator-based approach. Impact data are available to validate the risk assessment at the parish level and with this reveal key drivers of flood risk in different ecological regions of Ecuador. This information will provide the basis to derive targeted measures for disaster risk reduction.
The findings indicate that flood risk is largely driven by hazard-exposure, however, elements of vulnerability also shape risk in different ways. Overall, the heterogeneity between risk levels is higher between parishes than between provinces, which means that the high level of detail at parish level is very meaningful in this area. All of the very high-risk parishes can be found in Los Ríos, while more than half of Bolívar’s parishes have no risk (due to no hazard-exposure). The diversity in the risk pattern seems to be more linked to the boundary of ecological regions, with very high risk in the coastal lowland versus very low risk in the mountainous area. With regard to next steps, this assessment provides already an advanced methodological approach and could serve as a very good basis for deriving a national level flood risk assessment methodology for Ecuador.