Disasters are as old as human history but the dramatic increase and the damage caused by them in the recent past have become a cause of national and international concern. However, the poor suffer most from environmental disasters and are more vulnerable and less resilient to fluctuating climate because they live in areas that are at high risk to natural disasters and extreme weather. Also, they live in poorly built shelter that is easily damaged in the event of a disaster. Besides, they live in areas with few or no early warning programs. This book aims at contributing in the reduction of damages caused by flood to inhabitants of urbanized drainage basins by making use of spatial planning measures and flood zoning. To achieve this, the following had to be made: generating a database of elements at risk from scratch (with regard to the quasi inexistence of data in developing countries); mapping the hazard under investigation, evaluating the proportion of elements at risk and finally determining the return period of the hazard.