55 research outputs found
Changes in flood risk and perception in catchments and cities
Flash floods are often responsible for many deaths and involve many material damages. Regarding Mediterranean karst aquifers, the complexity of connections, between surface and groundwater, as well as weather non-stationarity patterns, increase difficulties in understanding the basins behaviour and thus warning and protecting people. Furthermore, given the recent changes in land use and extreme rainfall events, knowledge of the past floods is no longer sufficient to manage flood risks. Therefore the worst realistic flood that could occur should be considered. Physical and processes-based hydrological models are considered among the best ways to forecast floods under diverse conditions. However, they rarely match with the stakeholders' needs. In fact, the forecasting services, the municipalities, and the civil security have difficulties in running and interpreting data-consuming models in real-time, above all if data are uncertain or non-existent. To face these social and technical difficulties and help stakeholders, this study develops two operational tools derived from these models. These tools aim at planning real-time decisions given little, changing, and uncertain information available, which are: (i) a hydrological graphical tool (abacus) to estimate flood peak discharge from the karst past state and the forecasted but uncertain intense rainfall; (ii) a GIS-based method (MARE) to estimate the potential flooded pathways and areas, accounting for runoff and karst contributions and considering land use changes. Then, outputs of these tools are confronted to past and recent floods and municipalities observations, and the impacts of uncertainties and changes on planning decisions are discussed. The use of these tools on the recent 2014 events demonstrated their reliability and interest for stakeholders. This study was realized on French Mediterranean basins, in close collaboration with the Flood Forecasting Services (SPC Med-Ouest, SCHAPI, municipalities)
Operational tools to help stakeholders to protect and alert municipalities facing uncertainties and changes in karst flash floods
Flash floods are often responsible for many deaths and involve many material
damages. Regarding Mediterranean karst aquifers, the complexity of
connections, between surface and groundwater, as well as weather
non-stationarity patterns, increase difficulties in understanding the basins
behaviour and thus warning and protecting people. Furthermore, given the
recent changes in land use and extreme rainfall events, knowledge of the
past floods is no longer sufficient to manage flood risks. Therefore the
worst realistic flood that could occur should be considered.
Physical and processes-based hydrological models are considered among the
best ways to forecast floods under diverse conditions. However, they rarely
match with the stakeholders' needs. In fact, the forecasting services, the
municipalities, and the civil security have difficulties in running and
interpreting data-consuming models in real-time, above all if data are
uncertain or non-existent. To face these social and technical difficulties
and help stakeholders, this study develops two operational tools derived
from these models. These tools aim at planning real-time decisions given
little, changing, and uncertain information available, which are: (i) a
hydrological graphical tool (abacus) to estimate flood peak discharge from
the karst past state and the forecasted but uncertain intense rainfall; (ii) a
GIS-based method (MARE) to estimate the potential flooded pathways and
areas, accounting for runoff and karst contributions and considering land
use changes. Then, outputs of these tools are confronted to past and recent
floods and municipalities observations, and the impacts of uncertainties and
changes on planning decisions are discussed. The use of these tools on the
recent 2014 events demonstrated their reliability and interest for
stakeholders.
This study was realized on French Mediterranean basins, in close
collaboration with the Flood Forecasting Services (SPC Med-Ouest, SCHAPI,
municipalities)
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