Analysis of the French insurance market exposure to floods: a stochastic model combining river overflow and surface runoff

Abstract

Abstract. The analysis of flood exposure at a national scale for the French insurance market must combine the generation of a probabilistic event set of all possible but not yet occurred flood situations with hazard and damage modeling. In this study, hazard and damage models are calibrated on a 1995–2012 historical event set, both for hazard results (river flow, flooded areas) and loss estimations. Thus, uncertainties in the deterministic estimation of a single event loss are known before simulating a probabilistic event set. To take into account at least 90% of the insured flood losses, the probabilistic event set must combine the river overflow (small and large catchments) with the surface runoff due to heavy rainfall, on the slopes of the watershed. Indeed, internal studies of CCR claim database has shown that approximately 45% of the insured flood losses are located inside the floodplains and 45% outside. 10% other percent are due to seasurge floods and groundwater rise. In this approach, two independent probabilistic methods are combined to create a single flood loss distribution: generation of fictive river flows based on the historical records of the river gauge network and generation of fictive rain fields on small catchments, calibrated on the 1958–2010 Météo-France rain database SAFRAN. All the events in the probabilistic event sets are simulated with the deterministic model. This hazard and damage distribution is used to simulate the flood losses at the national scale for an insurance company (MACIF) and to generate flood areas associated with hazard return periods. The flood maps concern river overflow and surface water runoff. Validation of these maps is conducted by comparison with the address located claim data on a small catchment (downstream Argens).

An Innovative Damage Model for Crop Insurance, Combining Two Hazards into a Single Climatic Index

“…is part of the reflections. For many years, CCR has developed catastrophe models to evaluate the financial impact of natural disasters on residential and commercial insured values [17][18][19]. To improve knowledge on agriculture exposure to climatic events, CCR, in association with Agrocampus Ouest, is supervising a PhD project.…”

Stochastic rainfall fields time-series for probabilistic flood hazard assessment

“…Continuous simulation and/or heterogeneous rainfall fields are now well under investigation ( [4], [6], [14], [15]…). Continuous simulation does solve methodological problems, by allowing to take into account initial conditions (soil moisture and residual level of water in flood storage facilities), and by reproducing the real behavior of a set of flood mitigation structures under realistic heterogeneous rainfall events.…”

Coupling a global climatic model with insurance impact models for flood and drought: an estimation of the financial impact of climate change

“…As CCR is clearly exposed to the financial consequences of natural disasters occurring in France through the Nat Cat compensation scheme, it has been developing its own impact models: since 2003 for flood [1], 2005 for drought [2] and 2011 for storm surge [3]. These models are designed to fulfil two main objectives: -to estimate the financial impact of natural events, shortly after their occurrence, for insurance companies, for CCR and for the French state, i.e.…”

“…For each flood event, hourly rainfall data is integrated as an input into the in-house surface run-off model and then into the river overflow model developed by CCR [1].…”