Search

North Africa is characterized by several ungauged basins, especially in Morrocco, where satellite products could be an alternative of the lack ground-based measurements. In this study, the Land Parameter Retrieval Model (LPRM) soil moisture and the Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (GPM-IMERG) were used in flood modeling in Moroccan ungauged basins (Bourrous, Al Wiza, El Hallouf and Jamala). We started with comparing GPM-IMERG Early with ground measurements from five rain gauges. Next, the Soil Conservation Service – Curve Number (SCS-CN) was applied with ground precipitation measurements, LPRM and GPM-IMERG Early datasets to simulated flood events in a gauged basin, the Ghdat. Finally, this SCS-CN model was transposed with these satellite data sets validated to those ungauged basins in order to reproduce flood events. The results show that the GPM-IMERG Early is best with in situ measurements (correlation coefficient = 0.50; relative bias = 27.51%; probability of detection = 0.77; false alarm rate = 0.23), on a daily scale. The observed precipitation, LPRM and GPM-IMERG Early were performed well in validation to simulate floods in the Ghdat, where Nash–Sutcliffe criterion range from 0.43 and 0.98 using the SCS-CN model. For Bourrous, Al Wiza, El Hallouf and Jamala all flood events and hydrographs were reproduced by GPM-IMERG Early and LPRM products. Furthermore, LPRM products were validated against soil moisture measurements with a coefficient of determine R2 between 0.72 and 0.84. The results of this work provided interesting insights for flood modeling using GPM-IMERG and LPRM satellite products in ungauged basins. [ABSTRACT FROM AUTHOR]

River flooding has large societal and economic impacts across Africa. Despite the importance of this topic, little is known about the main flood generating mechanisms in Africa. This study is based on 13,815 flood events that occurred between 1981 and 2018 in 529 catchments. These flood events are classified to identify the different flood drivers: excess rains, long rains and short rains. Out of them, excess rains on saturated soils in Western Africa, and long rains for catchments in Northern and Southern Africa, are the two dominant mechanisms, contributing to more than 75% of all flood events. The aridity index is strongly related to the spatial repartition of the different flood generating processes showing the climatic controls on floods. Few significant changes were detected in the relative importance of these drivers over time, but the rather short time series available prevent a robust assessment of flood driver changes in most catchments. The major implication of these results is to underline the importance of soil moisture dynamics, in addition to rainfall, to analyze the evolution of flood hazards in Africa. [ABSTRACT FROM AUTHOR]