Résumé
In 2007, the WMO Executive Council, at its 66th session, recalled Resolution 16, which gives priority to the rescue and digitization of climate archives and to promote global and regional initiatives to collaborate on DARE (data rescue) and the exchange of scientific knowledge and related technological advances. The Council urged Members to make every effort to prevent the deterioration of climate-relevant data and to make these data available to support climate change analyses and relevant climate services. Within the framework of operational and scientific research actions around the updating of hydrological standards in West Africa (ActNAO project) and in response to the call of the WMO, we used the NUNIEAU software (NUmérisation de NIveaux d'EAU en mer ou en rivières - CEREMA's free software) which allows the digitization of all types of paper documents by automatic recognition. This software has been used on rainfall maps in Burkina Faso and Ivory Coast. The use of this tool allows rainfall analysis on an intraday time step, a time step that is very useful for the sizing of structures and networks, the knowledge and management of flash floods in small basins, particularly urban basins, and flood prevention actions... For example, Intensity-Duration-Frequency curves were reviewed and compared to old ones in order to follow the evolution of rainy events in a context of climate change in Burkina Faso and Côte d’Ivoire. The tendency would be an intensification of short duration rainfall. This product is intended to be disseminated and dedicated training courses have been organized for researchers and stakeholders in the South and North.