Jean-Claude Bader

Satellite data transmission and hydrological forecasting in the fight against Onchocerciasis in west Africa

Abstract Onchocerciasis, or river blindness, is an endemic disease which causes great hardship in west Africa. Within the World Health Organizations Onchocerciasis Control Program (WHO/OCP), reliable data on the discharge of the watercourses have been obtained by using remote satellite transmission. These data are necessary to calculate how much insecticide should be introduced into the rivers. A description of the equipment and its use is followed by an initial report covering the functioning of the equipment, its efficiency and the economies attained. The improvement in the resulting treatment and the reduction in the running costs of the programme are discussed. Software for forecasting the discharge over different time intervals was developed by ORSTOM at the request of the OCP. The different functions of this software (PERLES) are described. In conclusion, the advantages of remote transmission techniques for operational hydrology in general are discussed (flood warning systems, hydrological networks, etc.).

Modélisation de propagation d’écoulement entre lits mineur et majeur sur les fleuves Sénégal et Niger

RÉSUMÉ In the Senegal River valley and Niger Inner Delta, the annual floods inundate a wide floodplain consisting of a complex network of lakes and channels, where topographic information needed by standard hydraulic models is difficult to obtain. To represent the flood propagation between mainstream and floodplain, we use a model designed for flood propagation in river mainstreams with flat bed and large overflow and without topographic data. Depending on the water level in the riverbed, the model calibrated on the levels observed at two stations gives the level in the floodplains and propagation time between stations. Several cases are tested for various types of hydraulic connections between mainstream and floodplain. The model could correctly reproduce the flood rise and fall in the floodplain, even for a lake connected by a single channel to the riverbed or in the case of a strong attenuation of the flood between very distant stations.