Application of Remote Sensing and GIS to Assess the ConstructionPressure on the Environment of Algiers (Algeria) During the Three LastDecades and Their Evolution by the Use of Markov Chain

摘要

Like many cities in North Africa, limited in the south by steppe areas and indeed for some others by desert, its demography shows a steep rise, making a deep imbalance between the highly populated north and the south with a low population. This demographic pressure increased considerably during the period from 1990-2000, because of the extremely unstable political situation. This influx was accompanied by the development of new infrastructures (road and railway networks) and the densification of the economic fabric from 2005 onwards which led to the Algiers department being divided into three zones moving from North to South and in bands from East to West. These pressures were translated by a quick urban sprawl primarily along the Mediterranean ridge and secondarily inside the plain of Mitidja, precisely in the eastern part of the department in the context of an almost total absence of an official town development plan. Built up areas have increased spurred on by economic planning without preserving the balance between categories of land-use which has led to the disappearance of numerous wet zones, the reduction in underlying groundwater resources and the pollution of surface water in the main rivers crossing the plain. Cartographic analysis and the prediction of land-use at 2020 confirms the persistence of the process indeed its aggravation particularly near main roads and progressively inland creating new urban centres, even occupying flood plains (Oued El Harrach).