Development and validation of a grassland production index based on the use of satellite data time series: application to an insurance product in France.

Summary An index insurance is proposed in response to the increase in droughts affecting grasslands. It is based on a forage production index (FPI) obtained from medium spatial resolution satellite images to estimate the impact of the hazard in a defined geographical area. The main issue related to the implementation of such an insurance lies in the correct estimation of the losses incurred. The work of this thesis is based on two objectives: the validation of the IPF and the proposal of improvement of this index. A validation protocol is built to limit the problems related to the use of medium resolution products and to the change of scale. The IPF, when compared to different types of reference data, shows good performance: in situ production measurements (R² = 0.81. R² = 0.71), high spatial resolution satellite images (R² = 0.78 - 0.84) and data from modelling (R² = 0.68). The work also allows us to identify ways to improve the IPF processing chain. A new index, based on semiempirical modeling combining satellite data with exogenous data on climatic conditions and grassland phenology, improves the accuracy of production estimates by 18.6%. All of the results obtained open up numerous research perspectives on the development of the IPF and its potential application in the insurance field.