Ecology, Environment and Conservation Paper

IMPACT OF MORPHOLOGICAL FACTORS AND CLIMATE ON THE FLOODS IN ARID AREAS - CASE STUDY OF CATCHMENT OF THE VALLEY OF BECHAR, SOUTH-WEST, ALGERIA

Bouchiba Abdelhadi, Nabou Mohamed and Rezzoug Cherif

Abstract

Natural disasters, especially floods have always existed, on the world scale, they represent 34% of the natural disasters recorded between 1990 and 2007. The Algeria submitted to the floods that occur catastrophically thus constituting a major constraint for the economic and social development, including the more deadly are those of the last decade, such: Ghardaïa and Bechar (October 2008) Sidi Bel Abbots (2007), Bab El Oued (Algiers, 2004), Adrar (2004 and 2009) are marked by the magnitude of the human damage and/or materials. The present work is reserved for a presentation of the impact of the factors morphological and climate on floods, who among the most serious, which were known to the region are the floods of October 2008 caused by an intense precipitation with a height of 108,40 mm. Thirty-six hours of torrential rains without interruption, were sufficient to transform the city of Bechar and its periphery in gigantic torrents of mud and lead to the insulation completely from the city of Béchar, because of the collapse of the bridges that link the city by the national road in North and South, with a flow rate that exceeds 855 m3/s. It has also caused significant damage human and material. In addition, we are interested in the physical parameters such as the sections and the slope of the Vallée Béchar which is at the origin of the disaster. The profile in the length of the old shows a steeper slope, what produces an acceleration of flows, the calculation of sections of the old in different points reveals also variations at the level of the slope, which sub-intends to misbehaviour of the flow of water to the level of the reduced sections. Although it is, these investigations, alert us once again on the need of an integrated spatial development which takes account of regional specificities and in particular Natural Factors.