L’inondation en milieu urbain et le changement climatique dans le nord-est algérien étude de cas.

Abstract

The phenomenon of climate change, the causes of which are now known, can manifest itself in prolonged periods of drought, with adverse effects on the hydrological cycle, the environment and socio-economic activities. It is considered to be one of the major problems of sustainable development in the world because of its devastating consequences. Algeria, in recent years, has also made this one of its most important concerns. Indeed, since the 1990s, the climate change thesis has challenged water resources and the risks associated with them, placing them at the very heart of the problem. This study aims to identify the evolution of the main climatic parameters and its consequences on the hydrological cycle, in particular on the phenomenon of flooding in northeastern Algeria. This phenomenon is a recurring phenomenon all over the world and has affected most countries. In Algeria, it is one of the major challenges faced particularly by agglomerations in the North and South of the country. Various data and methods (climate indices, Bertin matrix, statistical method, spectral method, etc. ) were used. Application of these methods to rainfall series of 55 rainfall stations over a 43-year period (1969 – 2012) revealed a climate change characterized by a drought trend . Statistical methods indicate breaks between 1989 and 2002, indicating a change in rainfall patterns. These breaks are accompanied by a decrease in rainfall of 13 to 28%. The manifestations of this climate change affect water resources and particularly the character of runoff in the study area. The case of two agglomerations located in diametrically opposed environments and prone to flooding was selected to analyse the character of the flows: Annaba on the coast and Biskra at the gateway to the Sahara. The study concerns the Boudjamaa wadi, a river that drains the Annaba plain to the east of the Edough massif (mountains at an altitude of 1008 m), and the Biskra wadi, which runs through the town of the same name. On the basis of maps, plans, meteorological reports and historical documents, the analysis of the two urban sites and the history of the “flood” events made it possible to identify the risk and its respective perimeters within the cities.