Contribution of TRMM rainfall data to the study of natural systems and risk assessment. Cases of application in SW Angola

Abstract

Researchers studying exogenous processes in developing countries have to deal with the problem of scarcity of rainfall data. With satellite measurements, such as those provided by the Tropical Rainfall Measuring Mission (TRMM), it may be possible to overcome this limitation. In this work we link the TRMM rainfall measurements with two examples of exogenous processes from southwest Angola: landslide processes, focused on the events at the Leba road in early 2011, and flow conditions, based on the water level determined in gauging stations from rivers Cavaco and Catumbela. It is demonstrated that major mass flow movements occur when specific TRMM rainfall thresholds are reached. Regarding the flow conditions, the water level in two gauging stations is strongly conditioned by other factors beside the atmospheric precipitation in their watersheds (retention and release of water from reservoirs, channel obstruction, etc.), but short term oscillations are closely linked with the rainfall in the proximity. TRMM data is found to be very useful for the analysis of specific extreme events or the patterns of behavior of natural systems and, consequently, constitute a valuable tool in natural risks assessment.