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Natural Resource Monitoring in Africa (NARMA) is one of the Core Information Services of EU-FP7 project Geoland2
addressing important sectoral policies that concern with the development of an environmental monitoring capacity over
African countries for the needs of the European Commission (EC) services and for regional and continental EC partners
in African countries. Congo basin is one of the target area where NARMA has to contribute to the development of
AMESD/CICOS services in support to management of water resources focusing on environmental aspects of watersheds.
In this contest and to better understand dynamics that occur in the watershed, an analysis has been conducted on the
relation between precipitation, river discharge and vegetation dynamics by exploiting available time series of Earth
Observation data. Rainfall dynamics has been described using FEWS-NET RFE estimations, river discharge has been
monitored using ENVISAT radar altimeter data provided by LEGOS laboratory and vegetation dynamics have been
examined through vegetation indices available from long term series of SPOT-VGT data. The comparison between river
discharge measured at Bangui (Central African Republic), gauging station and radar altimeter virtual station data
demonstrated that these data can be used to estimate river discharge. This result allowed to focus a preliminary analysis
on the Uele watershed, Ubangi sub basin, using radar data as a proxy of river discharge, comparing these trends to
seasonal rainfall estimates and trying to disentangling the effect of vegetation on discharge-rain relation. Results showed
that a strong positive correlation is obtained between rain data and river discharge only at the end of the vegetation
season when plants have reduced water demand for evapotranspiration and less intercept rain. Trend analysis on the
considered time windows are provided and the contribution of these finding for river water alert monitoring system is discussed.
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