Abstract:
Understanding the space-time variations of extreme rainfall plays an important role in
the management of water-related disasters in Sahel countries. This study investigates temporal
changes in rainfall characteristics and explores the link between Atlantic Sea surface temperature and
extreme rainfall in the southern part of Burkina Faso. We find substantial spatial heterogeneity in
rainfall trends across the study area. In contrast to national and supra-national studies that found
predominantly increasing trends in extreme rainfall, we detect more downward than upward trends,
particularly for indices representing extreme rainfall. This difference is presumably a consequence of
the high spatial variability in rainfall trends that can only be detected with sufficiently dense climate
networks. We use the Poisson-General Pareto (Poisson-GP) distribution to quantify the frequency
and intensity of extreme rainfall. Our comparison of the traditional, stationary Poisson-GP model
with the nonstationary version where rainfall depends on Atlantic SST shows that the nonstationary
model outperforms the traditional approach. This finding suggests that the assumption of stationary
nature must be considered with care when modeling the frequency and intensity of extreme rainfall
in the study area. Overall, our results suggest that the recent increase in flood disasters in Burkina
Faso is rather caused by land use and land cover changes and population and urban growth and not
by increasing rainfall extremes.
Description:
A Publication submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université de Lomé, Togo in partial fulfillment of the requirements for the requirements for the degree of Doctor of Philosophy Degree in Climate Change and Disaster Risk Management
