La soutenabilité de la ville au Sahara entre compacité et tendances d’étalement urbain. Cas d’étude : Les grandes villes du Bas-Sahara algérien.

Abstract

Nowadays, urban sprawl is one of the major problems facing the Algerian Low-Sahara oases. Monitoring and understanding its spatial and landscape transformations, and the assessment of its consequences on oasis ecosystems, remain a key step in any oasis sustainability approach. The present study consists of highlighting different spatial growth of the biggest Algerian Low-Sahara cities during these last three decades. Through urban landscape ecology approach, our methodology is mainly based on the use of remote sensing data, by the application of Change Detection technic and landscape metrics. The comparison post-classification of multidates Landsat scenes has revealed a significant growth of built-up areas, with more accelerated rates during the period (2000 - 2015), against an excessive decline in palm groves, which is more accentuated during the period (1985 - 2000). The results of landscape metrics calculation have shown two distinctly opposite trends. A continual growth of built-up areas which tends more towards a morphological compacification of urban patches, against a progressive fragmentation of palm groves. Thus, this research has shown the importance of remote sensing in monitoring of uncontrolled urban sprawl, and the utility of adopted approaches of urban landscape ecology for measuring and assessment of its impacts, particularly in fragile environments like those of oases.