Abstract
Emerging parametric insurance products targeted at regional governments
consider an index of flooding as the instrument for payoff and rate
setting. Inundation extent from satellite remote sensing may provide a
more direct measure of flood risk in this context than hydraulic
modeling of flow and inundation. Here, we examine satellite-based
fractional inundated area as a proxy for flood impact that can be used
for index insurance payment at a regional scale. Typical methods for
estimating return periods from unbounded distributions such as the GEV
(generalized extreme value distribution) are not appropriate for
fractional flooded area, which is bounded by 0 and 1. Here we examine
alternative bounded distributions (2 parameter and a 4 parameter Beta)
to estimate return periods and quantify uncertainty using a bootstrap
sampling procedure for the short duration satellite record of fractional
flooded area. We consider two examples with distinct flood dynamics i) a
country (Bangladesh) where a flood can cover the majority of the land
surface, and ii) a river basin (the Rio Salado basin in Argentina) where
the worst flood covered only a modest fraction of the watershed. We
explore how a parametric insurance policy based on fractional flooded
area could be priced based on a typical approach used in the industry,
that accounts for uncertainty for small sample estimation. Our
exploratory approach to model selection illustrates how estimating the
uncertainty price influences insurance contract pricing and is important
to consider the choice of distribution beyond just the traditional
measures of goodness of fit.