An integrated modelling framework for climate change impact assessment on rice production and evaluation of adaptation strategies. A case study in Mali.

The aim of this PhD research was to describe an assessment of the potential impacts of climate change as well as climate variability on rice production. It also discusses selected adaptation options within the context of the Malian agriculture. The research centers on an integrated modelling approach (BioMA) to compute current and future (2020, 2050) crop yields in the agricultural region of the Office du Niger (Mali). BioMA – Biophysical Models Application – is a platform for running biophysical models on generic spatial units. The application is based on independent components which allow implementing modelling solutions targeted to specific modelling goals. The collected data were used to (i) develop new modules (a model for simulating the height of the plant) (ii) implement the existing ones according to the peculiarities of the sub-Saharan environment (i.e. the Agromanagement module was extended in order to take into account the beginning of the rainy season) and to (iii) calibrate and validate the modelling solution defined for the purpose. Although parameterization procedures were performed in critical conditions – being reference data from the area a limiting factor – a preliminary calibration of WARM, for tropical and subtropical conditions, could be performed aromatically on Chinese datasets. Indeed these results achieved from these modelling exercises showed that the model is robust and able to reproduce yield variability within years and locations which made it suitable for the impact assessment study in Mali. The impact assessment on cropping systems was evaluated via a difference analysis with respect to the current conditions, focusing on changes in total biomass, final yield and transpiration demand. An overall reduction can be expected in 2050 (up to complete failure of the crop) whereas different results were obtained for 2020. The main season seem to be little affected by the increase of temperatures whereas the first cycle, which takes already place under extremely high temperatures, will face reductions up to 25%. Based on the results obtained in the impact assessment changes in sowing dates were tested in order to detect the most suitable management techniques which allow alleviating the negative effect of climate changes. The results suggested that changes in the sowing may be very effective in mitigating the adverse effect of climate change as well as the use of new crop cultivars with longer vegetative cycles. In fact in both systems an increase of production can be expected at short-term whereas at medium-term the losses can be significantly reduced.