Johnny Douvinet

Flash Flood Hazard Assessment in Small Agricultural Basins Coupling GIS-Data and Cellular Automata Modelling: First Experimentations in Upper-Normandy (France)

Flash floods are the most dangerous processes in Seine-Maritime (northern France) due to their sudden onset and rapid rising time. Such floods shortly follow high rainfall, ranging from 50 to up to 100 mm in less than 6 hours, and occur in small (

Crowdsourcing and Crisis-Mapping in the Event of Floods: Tools and Challenges

Abstract: Crowdsourcing and crisis-mapping are concepts supported by the involvement of a large number of persons that enable, in a voluntary way, consolidation of information collected in situ during the course and progress of a phenomenon (such as a flood for example). The term ‘volunteerism’ is generally used to refer to activities that are non-obligatory (there is no contractual, familial or friendship obligation between the helper and the helped, nor coercion). Data collected is often of a geographical nature, and the tools used for collection (internet, mobile technologies), and publication of this data (websites, map platforms), enable it to be shared instantly and quickly. When floods occur, this input can help to assess the seriousness of a situation, and to guide disaster relief operations for victims.

14 – From Public Involvement to Citizen-based Initiatives: How Can Inhabitants Get Organized to Face Floods?

Abstract: Individuals have an increasingly significant role to play within flood prevention and management, as financial, material and human resources allocated to local authorities are on the decline, while stakes are still increasing. Institutions responsible for enforcing regulatory injunctions are unable to keep track of requested documents (status and compliance), to evaluate their effectiveness (induced behaviors), their reception and/or their understanding by all inhabitants living in flooded areas. Consequently over the last few years a certain number of citizen-based initiatives have emerged in response to such deficiencies. Each of these initiatives share a common goal: to reposition individuals at the heart of their own safety and to adapt regulations to local circumstances, or even to go beyond the focal point of a technocratic vision in favor of a more integrated and shared vision of risk. The form and content constituting these approaches is very diverse (comics, models, plays, videos, etc.) but even if it is clear that these initiatives complement the existing measures in place, they still fail to take into consideration institutional actors. Furthermore, political resonance and the involvement of many external actors weigh heavily in this area, resulting in citizen-led initiatives being a rare occurrence. Having highlighted the extent to which individuals are overlooked as a social and political reality, this chapter will seek to demonstrate the effectiveness of several citizen-based initiatives, the way they respond to specific needs and offer refined courses of action that work towards ensuring sustainability.

A smartphone application to help alert in case of flash floods

In France, government and specific services (SCHAPI) survey overflow stream floods (100.000km2) but flash floods characterized by fast, quick and dangerous responses (other 100.000km2) remain delicate to predict and difficult to monitor. Its about to explore the conditions of establishment of a proactive and innovative alert system via smartphones, to cope the risks associated with flash floods. The solution must be thought in way to achieve a major challenge: reducing the gap between a state approach (TOP-DOWN), which positions and imposed the state as the main official alert source, and the citizen action (Bottum-UP) which establishes the individual as “Citizen sensor” (both in go up or disseminate information) through the use of its smartphone. Addressing this challenge is indispensable if we hope effectively minimize material and human damages especially when high temporal acuity phenomena such as flash floods happen. Consequently, we propose to use Smartphone technologies: to reduce the time required to alert and to protect population; to enhance information observed by any people at local scales; to built automatic vigilance based on these “citizens-sensors”; to use field experiment to improve knowledge on flash floods actually available after damaged events; to use geo-location of transmitter sources to alert people located at 5 km around.

Spatial coexistence and temporal logout between mainland and marine hazards in Upper Normandy (NW France)

This paper focuses on the spatial coexistence between different hazards (strong west winds, beach sedimentary crisis and flash floods) in outlets of small catchments in a sedimentary basin. This study was carried out in the department of Upper Normandy located in north-western France. To anticipate possible future hazards and damages without depending on meteorological triggers (neither intense rainfall nor synoptic conditions), we combine previous knowledge accumulated on local phenomena to highlight the pre-conditioning factors and identify those areas characterised by the highest susceptibility to risk due to the accumulation of numerous hazards. This approach enables both space and time distribution patterns of natural hazards to be revealed. In space, the risk susceptibility strongly depends on morphology. Populations located at the outlet of large wet valleys, at the final outlets of small basins at a short distance from the plateaus and on the coastal fringe appear to be the most endangered. Even if hazards never occur at the same time, these areas can be affected by different hazards during one year (summer flash floods, floods, winter storm surges). This study identifies 14 sensitive areas along hollow shapes of the study area. Finally, our methodological investigations question the creation of a warning system combining mainland and marine hazards in these 14 outlets.